Search

Atomization involves disrupting a flow of contiguous liquid into small droplets ranging from one submicron to several hundred microns (micrometers) in diameter through the processes of exerting sufficient forces that disrupt the retaining surface tensions of the liquid. Understanding this phenomenon requires high-speed imaging from physical models or rigorous multiphase computational fluid dynamics models. We produce a MATLAB application that utilizes various methods of image analysis to quickly analyze and store mathematical data from detailed image analyses. We present a user with numerous tools and capabilities that provide results that deviate from 1.8% to 8.9% of the original image sequence depending on various factors. After comparing two-dimensional axisymmetric and planar cuts with the three-dimensional flat rendering, we found that the data is more dissimilar than similar based on analysis of mean, standard deviation, maximum, and minimum measurements.

Títol alternatiu emprat a la intranet docent de l'EPSEVG: "Dispensador automàtic d'aerosol amb propulsor natural", L'objectiu principal d'aquest projecte és millorar un dispensador d’aerosol automàtic per fer-lo més respectuós amb el medi ambient i ampliar el seu públic objectiu. En la comparació de diferents models d'aerosols, s'ha observat que tots són recarregables i tenen un preu semblant, però l'aspecte rellevant és el seu funcionament intern i els components de la fragància. Per millorar la sostenibilitat del producte, s’ha optat per utilitzar propel·lents d’origen natural i reformular la fragància. No obstant això, aquest canvi ha afectat el rendiment del dispositiu, provocant una disminució de la pressió interna a mesura que el refill es va buidant. La investigació se centrarà en estudiar com mantenir l'eficiència del dispositiu malgrat aquest canvi en la formulació de la fragància i complir les normatives mediambientals. Per això, es realitzen diversos assajos per determinar la millor combinació de formulació de la fragància i de propel·lent, així com estudiar com aquest canvi afecta el funcionament del dispositiu. També explorarem com aconseguir una polvorització uniforme de la fragància, tenint en compte els canvis en la formulació i en el mecanisme d'aspersió. Finalment s’extreuen les conclusions que confirmen si la producció d’aquest nou dispositiu es viable, en aquest cas caldrà realitzar més assajos ja que el temps i els recursos han sigut limitats. En resum, el nostre objectiu és desenvolupar un dispensador d’aerosol més sostenible i eficient, que compleixi amb les normatives mediambientals i mantingui la seva competitivitat en el mercat., The main objective of this project is to improve an automatic aerosol dispenser to make it more environmentally friendly and to expand its target audience. In comparing different aerosol models, it has been observed that all are rechargeable and have a similar price, but the relevant aspect is their internal operation and the components of the fragrance. To improve the product's sustainability, it was decided to use naturally derived propellants and reformulate the fragrance. However, this change has affected the device's performance, causing a decrease in internal pressure as the refill empties. The research will focus on studying how to maintain the device's efficiency despite this change in fragrance formulation and comply with environmental regulations. Therefore, various tests are being conducted to determine the best combination of fragrance formulation and propellant, as well as to study how this change affects the device's operation. We will also explore how to achieve a uniform spray of the fragrance, considering the changes in formulation and the spraying mechanism. Finally, conclusions will be drawn to confirm whether the production of this new device is viable. If so, further testing will be required as time and resources have been limited. In summary, our goal is to develop a more sustainable and efficient aerosol dispenser that meets environmental regulations and maintains its competitiveness in the market., Outgoing

Design of atomizers for gas-turbine purposes are an important ordeal. The per-formance of the atomizer directly impacts the efficiency of the gas-turbine, andconsequently, the energy extracted from the turbine. Furthermore, the design ofthe atomizer can have an impact on reducing toxic emissions. On a global scale,gas-turbines can be considered crucial for the transition to renewable energy. Forengineers, designing of atomizers are however challenging. Turbulent flow, multi-phase interaction and chemical reactions are some of the complex physics involvedwhich has to be taken into consideration when designing the atomizer. Engineerstraditionally uses experimental testing for investigation of designs, and it is still verymuch a useful methodology. However, numerical simulations and CFD have recentlygained popularity due to being a more cost-effective methodology. In this work, theprocedure for designing a prefilm atomizer involving CFD (single phase model andmulti phase model) and experimental testing is documented. The details of the twonumerical models (a single phase model and a multi phase model) has been doc-umented as well as the experimental setup. The single phase model is used for aparametric study and experimental testing is used for evaluation of designs. Themulti phase model is aimed to replicate the experimental results. The validity ofthe numerical models and the experimental setup are discussed, and possible mod-ifications of the methodology for future studies are suggested. Finally, suggestionsfor how the prefilmer should be designed is suggested.

Icing on aircraft wings is one of the leading causes of aircraft crashes. It is mainly caused due to accumulation of ice or snow on the wing surface due to impact with supercooled droplets when passing through clouds at high altitudes, causing loss of lift obtained by the wings. It was found that droplet impact characteristics are dependent on droplet size, surface roughness, surface material hydrophobicity, and droplet impact velocity. As a continuation of the study of droplet impact contact characteristics by varying surface roughness and impact velocity, this study focuses on droplets impacting the vibrating surface at frequencies between 2-7 kHz. Atomization (water drop splitting into smaller droplets and ejecting from the surface) has been observed at different rates for all frequencies. The first set of data is collected by keeping roughness constant and increasing the amplitude of the vibration to observe the critical amplitude at which atomization is initiated. The surface roughness is varied for the second set of experiments. The data is quantified using image processing of the high-speed videos to obtain the rate of ejection for each case.

Cracking of sugars to glycolaldehyde and other value-added oxygenates has shown potential in lab-scale fluidized beds with high yield and selectivity towards glycolaldehyde. In this work, a homogeneous gas-phase kinetics model for sugar cracking available in literature is adopted and implemented into the Computational Particle Fluid Dynamics (CPFD) framework in order to simulate sugar cracking in a pilot-scale circulating fluidized bed riser operated at conditions relevant for continuous production of glycolaldehyde in the industry. An Eulerian-Lagrangian approach is applied to model the three-phase flow where liquid feed droplets are injected into the hot gas-solid fluidized bed. A modified gas-to-liquid ratio dependent Rosin-Rammler droplet size distribution is proposed to accurately represent the gas-liquid jet in the simulation. Simulated temperature and pressure distributions are in good agreement with measured ones. Prediction of the yield of glycolaldehyde at 60.9 wt.%-C and other oxygenates using the the CPFD model corresponds closely to the results obtained from the same kinetic model implemented in an isothermal plug flow reactor model. This suggests that the CFB riser behaves essentially like a plug flow reactor, as hydrodynamic and thermal deviations from plug flow conditions do not have a considerable effect on the predicted yields. Comparing the model predictions to the measured yield of glycolaldehyde, a 50% overprediction is observed, suggesting that the hydrodynamic and cracking kinetics submodels need to be more closely coupled to more accurately predict the product yields, by means of e.g. heterogeneous cracking reactions.

In this study, a two-fluid nozzle, as, e.g., used in fluidized-bed or spray drying applications, is comprehensively characterized regarding the spray pattern and droplet size. To analyze the spray cone, the spray cone angle and the radial mass distribution of the nozzle were measured at varied liquid flow rate, spray air pressure, liquid insert bore diameter, and air cap position. Additionally, droplet size distributions were recorded at different spray settings. In general, the overall spray cone and single droplets are significantly influenced by the spray parameters, especially the spray air pressure, as well as the nozzle geometry.

A numerical framework used to model dense spray flames is proposed. In this framework, the liquid fuel (acetone) atomization is solved by a detailed high-resolution VOF simulation, and the Eulerian components of liquid droplets are transformed into Lagrangian droplets, which are stored in a database at a certain downstream cross-section. Then, the combustion process is solved by a LES/FPV (flamelet progress variable) adopting the pre-stored database of Lagrangian droplets (i.e., the position, size, and velocity of each droplet) as the inlet boundary conditions. This framework is a one-way coupling between a VOF simulation and a combustion simulation. The validity of this approach is investigated by comparing the computations with the experiments of the Sydney Piloted Needle Spray Burner. The VOF simulation shows that the volume flux of the droplets at the nozzle exit fluctuates both temporally and spatially and the larger droplets tend to be located away from the center axis compared to the small droplets. The computed breakup length is in good agreement with the empirical correlation. In the database of the Lagrangian droplets for the LES/FPV of spray flames, the location of the sampling cross-section, the sampling time, and the threshold value for Eulerian–Lagrangian (E-L) transformation strongly affect the properties of the Lagrangian droplets, and are critical for the successful use of the LES/FPV. Two spray flames with different recess distances are computed using their optimal pre-stored droplets databases and both show generally good agreement with the experiments in terms of the gas temperature and droplet size distributions. The spray flame with a longer recess distance, which is more representative of a dilute spray, is considered to have a longer and wider premixed core than that with a shorter recess distance representing a dense spray. The discrepancy in the prediction of denser spray flames becomes more evident leading to over-predictions of gas temper

The injection of liquid fuel at supercritical pressures is a necessary but overlooked topic in combustion. Under the premise that the liquid will swiftly transition to a supercritical state, the role of two-phase dynamics is typically ignored. Nevertheless, a transcritical domain exists for which a sharp interface prevails before substantial heating occurs. This transcrit- ical scenario may persist, for example, during the early deformation of liquid hydrocarbon fuels injected into high-pressure combustion chambers. Local thermodynamic phase equi- librium (LTE) enhances the dissolution of the oxidizing species into the liquid phase, and vaporization or condensation may occur simultaneously in several regions along with the in- terface. Following species and thermal mixing, fluid properties vary greatly, with liquid- and gas-mixture properties being more comparable near the interface. Small surface instabilities emerge early due to the combination of low, variable surface-tension force and gas-like liquid viscosities.The mixing process, interface thermodynamics, and early deformation of a cool liquid n- decane jet submerged into a hotter moving gas initially composed of pure oxygen are studied under different ambient pressures and gas velocities. For this purpose, a two-phase, low- Mach-number flow solver for variable-density fluids is proposed. Since the jet flow evolution corresponds to transitional turbulence, no turbulence models are considered. The interface is captured using a split Volume-of-Fluid method, generalized for a non-divergence-free liq- uid velocity. Both phases exchange mass across the interface. Numerical challenges emerge compared to incompressible two-phase algorithms, which are successfully addressed for the first time in this type of flow. The importance of transcritical mixing effects for increasing pressures is demonstrated. At first, local deformation features emerge, which differ signifi- cantly from earlier incompressible works. Then, ins

Ultrasonic waves generated by piezoelectric devices produce forces on fluids and particles that can be controlled to produce useful functions. The research field of acoustic microfluidics has developed fundamental understanding of these forces and demonstrated some useful functions, but it has yet to break through in industry and commercial use. We describe acoustic radiation force and acoustic streaming as well as some less common forces and review piezoelectric materials. Then we review some fundamental work in fluid mixing, translation, jetting, and atomization. Particle manipulation will also be touched on briefly, but it is not the focus. Instead, the focus of our work has been on producing droplets of liquid in air, either one at a time via jetting or many at a time via atomization We present a focused surface acoustic wave system in order to investigate the fundamental physics of jetting and to explore the possibility of some applications. We show that jetting must account for surface tension effects. Acoustic streaming is well understood to be the driving force behind jetting and its amplitude and direction are not dependent on surface tension in most literature because it is typically considered far from a deformable interface. However, jetting to produce a droplet is fundamentally an interfacial phenomenon and we show quantitatively how it should be accounted for in order to control droplet ejection angles. Our experimental system uses only two transducers, but it is not hard to imagine a system with four transducers that could control droplet ejection in two dimensions. This capability could be useful in printing by reducing the amount that the printing head has to translate. With this same focused surface acoustic wave device we demonstrate how frozen liquid can be melted and subsequently atomized. We also demonstrate a through-hole liquid supply that allows for continuous atomization and show that the angle control, similar to the jetting case, is possi

It is important to improve the thermal efficiency and reduce the harmful exhaust emissions of the direct-injection spark-ignition engine. However, this engine has problems such as the emission of particulate matter, including soot, from pool fire with luminous flames. Pool fire is caused by the thermal decomposition of a liquid film, which is created by fuel spray impinging on a piston surface. An understanding of liquid film formation process is important to reduce particulate matter. The purpose of this investigation was to evaluate the effects of injection pressure on fuel spray impingement and liquid film formation process, under engine motoring conditions, using the laser-induced fluorescence method. The fuel consisted of isooctane, 1-octanol and rhodamine B. 1-Octanol was the solvent for rhodamine B, which was illuminated with a neodymium-doped yttrium aluminum garnet laser, causing it to emit red fluorescence at a wavelength of 580 nm; the second harmonic of the laser is at 532 nm. Liquid film images were captured using a high-speed camera. Using image processing, the liquid film area, thickness and mass were estimated. It was found that increasing injection pressure increased the liquid film area, thinned the film and decreased the mass of fuel that remained. In total, 35.6% and 32.5% of the injection mass remained on the piston surface at an injection pressure of 5 and 13 MPa, respectively. In addition, the in-cylinder flow affected the liquid film formation process, stretching the film in the direction of the flow.

The inhaled route is regarded as one of the most promising strategies as a treatment against pulmonary infections. However, the delivery of drugs in a dry powder form remains challenging. In this work, we have used alginate to form microparticles containing an antibiotic model (colistin sulfate). The alginate microparticles were generated by atomization technique, and they were characterized by antimicrobial in vitro studies against Pseudomonas aeruginosa. Optimization of different parameters allowed us to obtain microparticles as a dry powder with a mean size (Feret diameter) of 4.45 ± 1.40 µm and drug loading of 8.5 ± 1.50%. The process developed was able to concentrate most of the colistin deposits on the surface of the microparticles, which could be observed by SEM and a Dual-Beam microscope. This produces a fast in vitro release of the drug, with a 100% release achieved in 4 h. Physicochemical characterization using the FTIR, EDX and PXRD techniques revealed information about the change that occurs from the amorphous to a crystalline form of colistin. Finally, the cytotoxicity of microparticles was tested using lung cell lines (A549 and Calu-3). Results of the study showed that alginate microparticles were able to inhibit bacterial growth while displaying non-toxicity toward lung cells.

Injection of gas–liquid sprays into gas–solid fluidized beds finds application in many industries. Effective mixing and distribution of liquid feed and solid bed material is paramount to ensure an efficient and profitable process. Despite its long-term use, the mechanism of liquid injection into gas–solid fluidized beds continues to raise questions and is only partially understood. This paper provides a thorough and up-to-date review of experimental and numerical investigations of gas–liquid sprays into gas–solid fluidized beds conducted over the past decades. Based on the surveyed literature, a phenomenological description of the prevalent mechanisms of gas–liquid injection under different operating conditions is presented. This review identifies suitable computational fluid dynamic models for simulating the mechanisms involved in gas–liquid–solid interactions along with recommendations for future numerical and experimental work.

Mixing layers between air and liquid are ubiquitous in nature and extremely common in industrial applications. Among the latest, air-assisted atomization is one of the predominant forcing used to induce breakup in liquid jets. In these flows, a low-momentum liquid jet and a high-momentum air stream are injected simultaneously along the same direction, separated only by a thin solid plate. The interaction between the two phases generates an instability that manifests in the form of flapping events, during which most of the droplets are created owing to the breakup of these liquid sheets. In this study, we discuss the statistical relevance of flapping events and how they contribute to determine the final droplet-size-distribution. We present an algorithm to isolate each event in Direct Numerical Simulations and discuss the dispersion between each event. Finally, we demonstrate the importance of performing this type of analysis to reveal of statistical properties of the droplet size distribution., QC 20240111

This study focuses on a statistical description of droplet sizes, created as a result of capillary-induced breakup of ligaments. Direct numerical simulations of air-water systems are employed by solving the two-phase Navier-Stokes equations on adaptive Octree grids (http://basilisk.fr/), using the VOF methodology coupled with height-function-based curvature modeling. Breakup of individual ligaments are triggered by initial surface corrugations, the dynamics of which are deterministic. Stochasticity is introduced in the mix by conducting an ensemble of simulations of slender corrugated ligaments, each realization corresponding to a random but unique initial configuration. Probability density functions of the droplet sizes are computed for different ensemble sizes. These results (fig. 1) combining the effects of stochasticity with the capillarity-driven nonlinear dynamics are compared to the predictions of a Gaussian random process theory for near-monochromatic waves, which facilitate our understanding of the nature of drop size distributions encountered in realistic and convoluted fluid fragmentation scenarios., QC 20240111

In contrast to the increasing aquaculture production of mussels worldwide, production in the European Union (EU) has shown a decreasing trend over the last two decades. Aquaculture production of mussels in the EU peaked in the late 1990s at more than 600 000 tonnes; by 2016, production volume had dropped by 20% to 480 000 tonnes. As mussel production represents more than ⅓ of EU aquaculture production, this decrease is an important contributor to the stagnation of EU aquaculture. Previous studies have suggested diseases, lack of mussel seed (spat), and low profitability as the main causes of the EU mussel production decrease. In this study, we investigate how economic and environmental factors have contributed. Moreover, we examine if the different mussel production techniques (raft, longline, on-bottom, and ‘bouchot’) have been differently affected, by analysing the economic performance and cost structure evolution for the period 2010–2016. We complement these results with a SWOT (strengths, weaknesses, opportunities, and threats) analysis of the EU mussel sector based on expert knowledge.

[ES] Existe un gran interés por las nuevas aleaciones de alta entropía, las cuales año a año se hacen nuevas investigaciones con resultados muy prometedores para el ámbito de la biomédica y la industria aeroespacial, entre otras. Este estudio sobre diferentes tecnologías de fabricación de estas aleaciones, en el que además se estudian dos nuevas aleaciones de alta entropía (Ti-Nb-Zr-Ta y Ti-Nb-Zr-Ta-Mo), no se ha podido llevar a cabo en su totalidad en el ámbito experimental, debido a la situación de emergencia por la pandemia de la Covid-19 que provocó el Estado de Alarma en los meses de marzo a junio de 2020 provocando el cierre de laboratorios, y con fuertes restricciones hasta la actualidad. Existen diferentes tecnologías para la fabricación de piezas, por lo que resulta interesante una comparación entre algunas de ellas. Una de las tecnologías más usadas es la pulvimetalurgia convencional, con su comparación y sinterización, pero esta tienes algunos problemas relacionados con la porosidad, por lo que resulta interesante probar una tecnología de alta densificación con el la sinterización por plasma de chispa. Así pues, en este proyecto se hace un análisis de las tecnologías más utilizadas para la fabricación de piezas, y una planificación y métodos, de todo el proceso de creación de las piezas y su estudio, donde se explica tanto la preparación de los polvos iniciales, fabricación de las probetas y su posterior caracterización. Se han propuesto estudios mecánicos, microestructurales y químicos, para poder obtener comparaciones tanto de las dos aleaciones como de las dos tecnologías de fabricación. También se ha realizado un presupuesto para conocer la cantidad económica que requiere implantar este proyecto en un laboratorio y llevar a cabo este proyecto en su totalidad para poder obtener todos los resultados necesarios y sacar conclusiones de ambas tecnologías y aleaciones., [CA] Hi ha un gran interès per les noves aliatges d'alta entropia, de les quals any rere any es fan noves investigacions amb resultats molt prometedors per a l'àmbit de l'enginyeria biomèdica i la indústria aeroespacial, entre d'altres. Aquest estudi sobre diferents tecnologies de fabricació d'aquests aliatges, en què a més s'estudien dues noves aliatges d'alta entropia (Tu-Nb-Zr-Ta i Tu-Nb-Zr-Ta-Mo), no s'ha pogut dur a terme íntegrament en l'àmbit experimental, a causa de la situació d'emergència per la pandèmia de la Covid-19 que va provocar l'Estat d'Alarma en els mesos de març a juny de 2020 provocant el tancament de laboratoris, i amb fortes restriccions fins a l'actualitat . Hi ha diferents tecnologies per a la fabricació de peces, pel que resulta interessant una comparació entre algunes d'elles. Una de les tecnologies més usades és la pulverimetal·lúrgia convencional, amb la seva comparació i sinterització, però aquesta tens alguns problemes relacionats amb la porositat, pel que resulta interessant provar una tecnologia d'alta densificació com la sinterització per plasma d'espurna. Així doncs, en aquest projecte es fa una anàlisi de les tecnologies més utilitzades per a la fabricació de peces, i una planificació i mètodes, de tot el procés de fabricació de les peces i el seu estudi, on s'explica tant la preparació de les pols inicials , fabricació de les provetes i la seva posterior caracterització. S'han proposat estudis mecànics, microestructurals i químics, per poder obtenir comparacions tant de les dues aliatges com de les dues tecnologies de fabricació. També s'ha realitzat un pressupost per conèixer la quantitat econòmica que requereix implantar aquest projecte en un laboratori i dur a terme aquest projecte en la seva totalitat per poder obtenir tots els resultats necessaris i treure conclusions d'ambdues tecnologies i aliatges., [EN] There is great interest in new high entropy alloys, of which new research is carried out year after year with very promising results for the field of biomedical engineering and the aerospace industry, among others. This study on different manufacturing technologies for these alloys, in which two new high entropy alloys (Ti-Nb-Zr-Ta and Ti-Nb-Zr-Ta-Mo) are also studied, has not been carried out in its entirety in the experimental field, due to the emergency situation due to the Covid-19 pandemic that caused the State of Alarm in the months of March to June 2020, causing the closure of laboratories, and with strong restrictions until now. There are different technologies for the manufacture of parts, so a comparison between some of them is interesting. One of the most used technologies is conventional powder metallurgy, with its comparison and sintering, but this has some problems related to porosity, so it is interesting to try a high-density technology such as spark plasma sintering. Thus, in this project an analysis of the technologies most used for the manufacture of parts is made, and a planning and methods of the entire process of manufacturing the parts and their study, where both the preparation of the initial powders, manufacture of the specimens and their subsequent characterization. Mechanical, microstructural and chemical studies have been proposed in order to obtain comparisons of both the two alloys and the two manufacturing technologies. A budget has also been made to know the economic amount required to implement this project in a laboratory and carry out this project in its entirety in order to obtain all the necessary results and draw conclusions from both technologies and alloys.

[ES] El presente Trabajo Fin de Grado ha sido realizado con la finalidad de entender la influencia de las condiciones de contorno en el proceso de atomización de un quemador de flujo continuo. Para ello se han utilizado distintos combustibles, siendo elegidos por las diferencias de sus propiedades físicas. Los ensayos se realizaron a diferentes condiciones de contorno, destacando la variación de la temperatura y el flujo másico del aire. Adicionalmente se ensayó a distintas presiones de inyección y geometrías de salida del aire. Por último, para determinar la velocidad de las gotas se ha utilizado la técnica óptica llamada PIV, ¿Particle Image Velocimetry¿., [EN] The present Project has been made in order to understand the influence of the boundary condition on the atomization process of a continuous flow burner. Various fuels were used; they have been chosen because of the differences of their physical properties. The experiments were realized under different boundary conditions, emphasizing the temperature and air mass flow variations. Additionally, different injection pressures and air outlets geometries were tested. Lastly, an optical technique has been used in order to study the drops velocities which is called PIV, Particle Image Velocimetry.

The idea of an aerospike engine exists since the 1950s. The main advantage of such a concept is theability to adapt the nozzle exit pressure according to the ambient pressure which makes it more efficientthan classic bell nozzles. This work assesses the design and analyse an injector for an annular aerospikewhich shall be propelled with High-test Peroxide (HTP) and kerosene (Jet-A). The engine shall generate6,000 Newtons of thrust and manufactures with Additive Layer Manufacturing (ALM). Aerospikeengines are exotic engines and still remain experimental engines due to lack of ground and flight tests.However, recent innovations (especially in the field of ALM) allow to solve most of the engines problems.One of them is the low combustion efficiency. In an annular aerospike, the centre spike can be seenas an obstacle as it prevents a homogeneous distribution during injection inside the combustion chamber.Many different injector types have been investigated and compared with each other. A radial injectorwhich in the first line allows a homogeneous fluid distribution inside the chamber has been selected.The next step was to determine the oxidiser-fuel-ratio, amount of injector elements, total pressure drop,and the atomization characteristics of the selected injector layout. The analytical calculation is based onexperimental data that is adapted for this application if required.The last step contains a short numerical set-up for calculating the pressure drop. Unfortunately, dueto lack of computational performance available no further investigation about the injector characteristiccould be performed. The numerical set-up can be used as an aid to understand the behaviour of thepressure drop. The results show that it is analytically possible to calculate the pressure drop of a complexshaped injector nozzle. The last and final step in order to verify all the results is to perform cold flow testto measure the pressure drops and discharge coefficient, droplet formations and dist

In contrast to the increasing aquaculture production of mussels worldwide, production in the European Union (EU) has shown a decreasing trend over the last two decades. Aquaculture production of mussels in the EU peaked in the late 1990s at more than 600 000 tonnes; by 2016, production volume had dropped by 20% to 480 000 tonnes. As mussel production represents more than ⅓ of EU aquaculture production, this decrease is an important contributor to the stagnation of EU aquaculture. Previous studies have suggested diseases, lack of mussel seed (spat), and low profitability as the main causes of the EU mussel production decrease. In this study, we investigate how economic and environmental factors have contributed. Moreover, we examine if the different mussel production techniques (raft, longline, on-bottom, and ‘bouchot’) have been differently affected, by analysing the economic performance and cost structure evolution for the period 2010–2016. We complement these results with a SWOT (strengths, weaknesses, opportunities, and threats) analysis of the EU mussel sector based on expert knowledge.

[ES] La regulación de emisiones de los motores de combustión interna alternativos, y las futuras, son y van a ser cada vez más restrictivas. Es por ello que los sistemas de post-tratamiento están siendo cada vez más investigados y optimizados. En este trabajo se propone el uso del código comercial de CFD CONVERGE para la simulación del proceso de inyección de AdBlue (disolución de agua-urea, UWS) en los sistemas de reducción catalítica (SCR). Para ello se empleará un enfoque Euleriano-Lagrangiano para el flujo multifásico con métodos RANS para la turbulencia. Los resultados obtenidos se compararán y validarán con experimentos realizados en el Departamento. El principal objetivo del proyecto es mejorar la precisión en la predicción de la distribución de gotas, además del estudio de la conversión del AdBlue en Amoniaco., [EN] The regulation of emissions of alternative internal combustion engines, and future ones, are and will be increasingly restrictive. That is why post-treatment systems are being increasingly investigated and optimized. In this work, the use of the commercial code of CFD CONVERGE is proposed for the simulation of the injection process of AdBlue (urea-water solution, UWS) in catalytic reduction systems (SCR). For this, an Eulerian-Lagrangian approach will be used for multiphase flow with RANS methods for turbulence. The results obtained will be compared and validated with experiments carried out in the Department. The main objective of the project is to improve the precision in the prediction of droplet distribution, in addition to studying the conversion of AdBlue into Ammonia.

[ES] Desde sus inicios, el crecimiento de la industria aeroespacial ha estado ligado a la investigación, desarrollo e implementación de tecnologías punteras en sus sistemas y vehículos. En la actualidad, la masificación de los cielos derivada del aumento en número y frecuencia de los vuelos comerciales plantean un desafío medioambiental sin precedentes. En este sentido, ahondar en la comprensión de los procesos de inyección y atomización del combustible en fase líquida es fundamental para garantizar una combustión completa y eficiente con niveles mínimos de emisiones contaminantes. Con tal objetivo, el presente Trabajo Final de Máster se centra en la caracterización del flujo interno y de las estructuras formadas tras la atomización primaria en un inyector ¿pressure-swirl¿, ampliamente usado en los motores de turbina de gas aeronáuticos. Estos atomizadores hacen uso de la presión como mecanismo de acción para impulsar el combustible a través de sus canales tangenciales, dotando así al flujo interno de una componente rotatoria que permite expedir el combustible en forma de spray cónico hueco. En particular, un atomizador comercial del suministrador Danfoss es objeto de estudio. En una primera etapa, se determinan sus dimensiones características con el uso de técnicas experimentales, como la medición de las piezas y moldes de silicona de la geometría interna mediante microscopio óptico y electrónico (SEM). De esta forma, se define la geometría de referencia empleada para configurar el posterior estudio CFD (Computational Fluid Dynamics). El estudio computacional consiste en el análisis del flujo interno y del spray externo generado por el atomizador Danfoss, ya caracterizado. Para ello, se llevan a cabo simulaciones LES (Large Eddy Simulations) en un dominio representativo del campo cercano a la salida del atomizador, introduciéndose herramientas de mallado automático para capturar con detalle los fenómenos físicos responsables de la rotura de la lámina de combustible, [EN] Since its very beginning, aerospace industry growth has been closely related to the investigation, development and implementation of cutting-edge technologies into their systems and vehicles. Nowadays, overcrowded sky due to the increase in number and frequency of commercial flights represents an unprecedented environmental challenge. In this sense, to deepen in the comprehension of the injection and atomization processes of liquid fuel is essential to guarantee a complete and efficient combustion with minimum levels of polluting emissions. To achieve that goal, this Master's Thesis Project focuses onto the characterization of the internal flow and main flow structures formed once primary atomization occurs in a ¿pressure-swirl¿ injector, which is widely extended among gas turbine aeronautical engines. These atomizers use pressure forces as driven mechanism to guide the fuel through their tangential ports in order to provide a whirling motion to the internal flow, which makes the fuel emerge as a hollow-cone spray. Particularly, an atomizer commercially distributed by Danfoss is studied. At a first stage, its characteristic dimensions are determined by experimental techniques, such as optical and electronic microscopy (SEM) measurements of pieces and silicone molds regarding the internal atomizer geometry. Thereby, the reference geometry used to configure the subsequent CFD study (Computational Fluid Dynamics) is defined. The computational study consists in the analysis of the internal flow and external spray generated by the Danfoss atomizer, already characterised. For that purpose, LES (Large Eddy Simulations) simulations are carried out for a representative domain that contains the field close to the atomizer outlet, where advanced meshing tools are introduced to capture the physical phenomena responsible for the sheet breakup into a wide variety of ligaments and drops with sufficient detail. These advanced techniques, known as Adaptive Mesh Refinement (AMR), [CA] El present Treball Final de Master se centra en la caracteritzaci ` o del ´ flux intern i de les estructures formades despres de l’atomitzaci ´ o prim ´ aria en un injector ` “pressure-swirl”, habitualment empleat en els motors de turbina de gas aeronautics. Aquests ` atomitzadors utilitzen la pressio com a mecanisme d’acci ´ o per a impulsar el combustible a ´ traves dels seus canals tangencials, dotant aix ´ ´ı al flux intern d’una component rotatoria que ` permet expedir el combustible en forma de spray conic vuit.

[ES] La emisión continua de gases de efecto invernadero (CO2 , N2 O, H2 O, etc) y de compuestos contaminantes (NOx , HC, hollín, etc), por parte del sector del transporte, ha generado un movimiento de preocupación medioambiental a nivel global. En consecuencia, las normativas anti-contaminantes han implantado medidas más restrictivas, obligando a la industria automovilística al desarrollo de nuevas tecnologías que sean menos dañinas para el ecosistema. La inyección directa de gasolina (GDi) surge como una solución capaz de disminuir las emisiones, puesto que, al poder trabajar con mezclas estratificadas, aumenta el rendimiento térmico del motor. La combustión bajo estas condiciones de operación necesita que el proceso de atomización y mezcla del combustible se lleve a cabo en un corto periodo de tiempo. Por tanto, una correcta caracterizacón de estos fenómenos va a permitir mejorar el diseño de las inyecciones. La mecánica de fluidos computacional (CFD) es una herramienta fundamental para el avance de la tecnología GDi, con ella es posible obtener resultados numéricos, mediante la modelización de múltiples fenómenos (turbulencia, flujo multifásico, atomización, etc), que son imposibles de resolver de forma analítica. En este proyecto se ha realizado un estudio del flujo externo de la inyección en un motor GDi, bajo los estándares establecidos por la Engine Combustion Network (ECN). Se ha hecho uso del software CONVERGE v2.4, en el que se ha optado por una aproximación Euleriana-Lagrangiana para la modelización del flujo bifásico y un enfoque LES para modelar la turbulencia., [EN] The continuous emission of greenhouse gases (CO2 , N2 O, H2 O, etc) and polluting compounds (NOx , HC, sutge, etc), by the transport sector, has generated a movement of global environmental concern. As a result, anti-pollution regulations have introduced greater restrictive measures, forcing the automobile industry to develop new technologies that are less harmful to the ecosystem. Gasoline direct injection (GDi) has emerged as a solution capable of reducing emissions, since being able to work with stratified mixtures increases the thermal efficiency of the engine. Combustion under these operating conditions requires the atomization and fuel mixing process to be carried out in a short period of time. Therefore, a correct characterization of these phenomena will allow to improve the design of the injections. Computational Fluid Dynamics (CFD) is a fundamental tool for the advance of GDi technology, it makes it possible to obtain numerical results by modeling multiple phenomena (turbulence, multiphase flows, atomization, etc), which are impossible to solve analytically. In this project, a study of the external injection flow in a GDi engine has been carried out under the standards established by the Engine Combustion Network (ECN). The CONVERGE v2.4 software was used in this proyect, in which an Eulerian-Lagrangian approach was chosen for modeling multiphase flow and a LES approach for modeling the turbulence., [CA] L’emissió contínua de gasos d’efecte hivernacle (CO2, N2O, H2O, etc) i de compostos contaminants (NOx, HC, sutge, etc), per part del sector del transport, ha generat un moviment de preocupació mediambiental a nivell global. En conseqüència, les normatives anti-contaminants han implantat mesures m ́es restrictives, obligant a la industria automobilística al desenvolupament de noves tecnologies que siguin menys perjudicials per a l’ecosistema. L’injecció directa de gasolina (GDI) sorgeix com una solució capa ̧c de disminuir les emissions, ja que, al poder treballar amb mescles estratificades, augmenta el rendiment tèrmic del motor. La combustió sota aquestes condicions d’operació necessita que el procés d’atomització i barreja del combustible es dugui a terme en un curt període de temps. Per tant, una correcta caracterització d’aquests fenòmens permetrà millorar el disseny de les injeccions. La mecànica de fluids computacional (CFD) ́es una eina fonamental per a l’avanç de la tecnologia GDi, amb ella ́es possible obtenir resultats numèrics, mitjan ̧cant la modelització de múltiples fenòmens (turbulència, flux multifàsic, atomització, etc.), que s ́on impossibles de resoldre de manera analítica. En aquest projecte s’ha realitzat un estudi del flux extern de la injecció en un motor GDi, sota els estàndards establerts per la Engine Combustion Network (ECN). S’ha fet ́us del software CONVERGE v2.4, on s’ha optat per una aproximació Euleriana-Lagrangiana per a la modelització del flux bifàsic i un enfocament LES per modelar la turbulència.

Soft robotics is a promising field that can solve several limitations of traditional rigid robotics. These systems are composed of soft and flexible materials to achieve high degrees-of-freedom and compliance with their surroundings. An important part of soft robotics is developing methods to actuate the soft structures. A popular method involves inflating soft hollow structures with a pneumatic pump that can achieve rapid and precise actuation. However, the structure must be tethered to a heavy and rigid pump, which limits its application. An alternative method vaporizes embedded liquid to inflate the structure instead. The simplest and widely used design to vaporize such liquid is by installing a heating element near the liquid. Heating the system beyond the boiling point rapidly boils the liquid and deforms the structure. The small amount of liquid and heater makes it easier to be packaged into a portable device. Nevertheless, this technique possesses several limitations that must be improved to be practical. This dissertation addresses these limitations and introduces methods that can advance the field for future robotics. Chapter 2 describes how actuation through vaporization can be affected by the environment and introduces a system that consists of double-layered walls and a thermoelectric device. Chapter 3 aims to implement ultrasonic waves that propagate through materials, which enables a system with detachable parts. Chapter 4 utilizes vibrating mesh atomization to drastically improve the slow actuation speed by evaporating small droplets with large surface areas. Last, chapter 5 introduces a method that can potentially remove electrical components by combining ultrasonics with shape optimization. These studies show that soft actuation through vaporization has significant room for improvement and can potentially replace commercial actuation methods with further optimization.

[EN] Primary atomization and initial spray development are critical in the operation of high-pressure liquid sprays such as the ones used in internal combustion engines. In the current paper, an analysis of the effect of the fuel injection pressure on the near-nozzle spray morphology is performed. For this purpose, a high-magnification diffused backlight imaging technique is set by means of a high-speed light-emitting diode and a long-distance microscope. The technique allows to visualize the first 2 mm of the spray development with a resolution of approximately 250 pixels per millimeter. The images obtained are processed with two different criteria to define the spray contour: one using an optical thickness threshold and a second one based on the intensity derivative on the radial direction. The analysis is focused on three aspects of the spray morphology: the spray angle, its standard deviation, and the standard deviation of the spray contour itself. The results show that the average spray angle is only slightly affected by the injection pressure, being the discharge density the main boundary condition affecting this parameter. Instead, the two standard deviation parameters show a clear increasing trend with the injection pressure, confirming that higher turbulence at the nozzle outlet induces higher variability in the spray shape. Regarding the two contour detection methodologies, similar values are reached in the average spray angle, while some more impact is seen in the spray dispersion, although the same trends are found

Optimal management of chronic rhinosinusitis (CRS) endotypes includes post-operative application of topical formulations. There is little evidence regarding the ideal aerosol delivery characteristics and techniques to achieve the most efficient deposition on affected sinus mucosa. Nebulisers provide an alternative to nasal sprays by producing smaller particle sizes at lower velocities. We applied a reverse-particle-tracking simulation using computational fluid dynamics (CFD) to evaluate the ideal aerosol characteristics from a nebuliser to target the post-operative maxillary sinus mucosa. A CT scan of a CRS patient was used to create a pre-operative and virtual post-operative model. Particles of diameter 2 to 30 µm were tracked through the sinonasal cavity at 5, 10 and 15 L min–1 flow rates using CFD. Reverse particle simulations demonstrated that the optimised combination of parameters were 20 µm particles, delivered at 5 m s–1 (or 14 microns, delivered at 15 m s–1) at an inhalation rate of 5 L min–1, released from a nozzle in an elliptical oblique-superior direction into the superior half of the nasal valve significantly improved the maximum deposition efficiency (from 3% up to 55%) in the post-operative maxillary sinus mucosa. The nebulised spray (without optimisation) demonstrated negligible particle deposition within the sinuses of the pre-op model, while it increased marginally in the post-op model for smaller diameter particles at lower inhalation rates. The ideal combination of parameters to achieve targeted medication deposition on specific sinus mucosal surfaces can guide the development of new nasal drug delivery devices that produce the desired deposition regions for clinical applications in post-operative CRS patients.

Recently, processes of social struggles emerged that questioned social inequalities and injustices. The experiences of Chile and Hong Kong are examples of how the mobilization and protest of the citizenry have called for greater democratization using information and communication technologies. From an interdisciplinary perspective that recovers theoretical proposals from classical thinkers of philosophy and socio-anthropological contributions, we reflect through ethical questions on the political and social use of TICs to account for the real and disruptive virtuosity they present regarding the viralization of an atomized life., Los usos y efectos de las tecnologías de la información y comunicación (tic) no se encuentran predeterminados. Su utilización en procesos de movilización y protesta social renuevan las discusiones sobre las potencialidades que pueden adquirir socialmente, en cuanto medios virtuosos para reclamar justicia social y una mayor democratización. Desde una mirada interdisciplinaria que recupera propuestas teóricas de pensadores clásicos de la filosofía y aportes socioantropológicos, reflexionaremos mediante interrogantes éticos sobre la potencialidad de los usos políticos y sociales de las tic para dar cuenta de una virtuosidad real y disruptiva, con respecto al predominio de una vida atomizada., Recentemente, surgiram processos de lutas sociais que questionam as desigualdades e injustiças sociais. As experiências do Chile e Hong Kong são exemplos de como a mobilização dos cidadãos pediram uma maior democratização usando as tecnologias da informação e comunicação. De uma perspectiva interdisciplinar que recupera propostas teóricas de pensadores clássicos da filosofia e contribuições sócio-antropológicas, refletiremos através de questões éticas sobre o uso político e social das TICs para explicar o virtuosismo real e perturbador que eles apresentam em relação à viralização de um vida atomizada.

In this research, an instant powder was elaborated and characterized physico-chemically, functionally and sensorially to prepare a milk drink enriched with cassava flour (Manihot esculenta C.), using spray drying. Drying was performed at 140 ° Cand air speed of 0.45m3 / min, formulations were evaluated at 15%, 10% and 5% addition of cassava flour; The dietary fiber contents, humidity, pH, acidity, fats, proteins, cyanide content (HCN), Brix degrees, carbohydrates, water adsorption capacity and solubility were evaluated.The dehydrated formulations showed percentages of dietary fiber content of 4.50%, 3.82% and 3.67%, humidity between 2.48% and 2.95%, and protein contents of 25.05% and 23, 32%. The powders showed good characteristics of (WAC) and solubility, allowing it to be used as an instant drink. Formulation 1 presented good sensory acceptability and coverage of 7% of the daily fiber requirement for children under 4 years; identifying itself as a product of high nutritional value., La fibra, es el material vegetal de importancia medicinal más estudiado en la actualidad, esto debido a sus aportes en el mantenimiento y sostenimiento de la salud, en especial del sistema digestivo. En esta investigación se planteó la utilización del secado por atomización para elaborar una bebida láctea instantánea enriquecida con harina de fibra de Yuca (Manihot esculenta C) y su caracterización fisicoquímica, funcional y de aceptabilidad sensorial. El secado se realizó a 140°C, se evaluaron formulaciones a 15%, 10% y 5 % de adición de harina de yuca; se evaluaron los contenidos de fibra dietética, humedad, pH, acidez, grasas, proteínas, contenido de cianuro (HCN), grados Brix, carbohidratos, capacidad de adsorción de agua y solubilidad. Las formulaciones deshidratadas mostraron porcentajes de contenido de fibra dietaría de 4,50%, 3,82% y 3,67%, humedades entre 2,48% y 2,95%, y contenidos de proteína de 25,05% y 23,32%. Los polvos mostraron buenas características de capacidad de absorción de agua (CAA) y solubilidad, permitiéndole ser utilizado como una bebida instantánea. La formulación 1, presento una buena aceptabilidad sensorial y cubrimientos del 7% del requerimiento diario de fibra para menores de 4 años; identificándose como un producto de alto valor nutricional.

The uses and effects of information and communication technologies are not predetermined. Its use in recent processes of mobilization and social protest renews the discussions about the potentialities that they can acquire in social life as virtuous means to demand social justice and greater democratization. From an interdisciplinary perspective that recovers theoretical proposals from classical thinkers of philosophy and socio-anthropological contributions, we reflect through ethical questions on the political and social use of icts to visualize the real and disruptive virtuosity they present regarding an atomized life., Los usos y efectos de las tecnologías de la información y comunicación (tic) no se encuentran predeterminados. Su utilización en procesos de movilización y protesta social renuevan las discusiones sobre las potencialidades que pueden adquirir social-mente, en cuanto medios virtuosos para reclamar justicia social y una mayor demo-cratización. Desde una mirada interdisciplinaria que recupera propuestas teóricas de pensadores clásicos de la filosofía y aportes socioantropológicos, reflexionaremos mediante interrogantes éticos sobre la potencialidad de los usos políticos y sociales de las tic para dar cuenta de una virtuosidad real y disruptiva, con respecto al pre-dominio de una vida atomizada.

Plain-jet airblast atomizers are widely used in industrial applications. The literature contains numerous papers on Sauter mean diameter, however, there is no estimation method available for spray cone angle, SCA, which derivation is the primary goal of this study. Four distinct, practical model liquids were analyzed: distilled water, diesel oil, light heating oil, and crude rapeseed oil. The atomizing pressure and liquid preheating temperature were varied in the range of 0.3–2.4 bar and 25–85 °C, respectively. This latter parameter enabled a wide and continuous liquid kinematic viscosity investigation range of 0.33–44.2 mm2/s. The resulting sprays were imaged at various shutter speeds for proper edge detection. An adaptive thresholding algorithm was developed in Matlab software environment to calculate SCA. The methodology is discussed in detail to facilitate the re-implementation of this technique since there is no generally accepted method for SCA measurement. SCA inversely varied with liquid density and followed a power law with the air-to-liquid mass flow ratio; however, the derived expression also performed well by replacing air-to-liquid mass flow ratio by either Mach number or momentum flux ratio. A simple empirical equation was derived, which allows the estimation of SCA of airblast atomization in a wide parameter range within a 3.5% deviation. The measured results were evaluated in the light of high-speed camera images in the vicinity of the nozzle; it was found that increased liquid jet breakup length decreases SCA while intense ligament formation increases it.

[EN] Engine fuel spray modeling still remains a challenge, especially in the dense near-nozzle region. This region is difficult to experimentally access and also to model due to the complex and rapid liquid and gas interaction. Modeling approaches based on Lagrangian particle tracking have failed in this area, while Eulerian modeling has proven to be particularly useful. Interface resolved methods are still limited to primary atomization academic configurations due to excessive computational requirements. To overcome those limitations, the single-fluid diffuse interface model known as Sigma-Y, arises as a single-framework for spray simulations. Under the assumption of scale separation at high Reynolds and Weber numbers, liquid dispersion is modeled as turbulent mixing of a variable density flow. The concept of surface area density is used for representing liquid structures, regardless of the complexity of the interface. In this work, a LES based implementation of the Sigma-Y model in the OpenFOAM CFD library is applied to simulate the ECN Spray A configuration. Model assessment is performed for both near- and far-field spray development regions using different experimental diagnostics available from ECN database. The CFD model is able to capture near-nozzle fuel mass distribution and, after Sigma equation constant calibration, interfacial surface area. Accurate predictions of spray far-field evolution in terms of liquid and vapor tip penetration and local velocity can be simultaneously achieved. Model accuracy is lower when compared to mixture fraction axial evolution, despite radial distribution profiles are well captured.

[EN] The present work analyses the effect of the eccentricity of diesel nozzle orifices over the spray behaviour by means of CFD simulations. Several orifice geometries with varying horizontal eccentricity (from 0.50 to 0.94) are selected. Their performance is assessed at a high injection pressure of 200 MPa, a 3 MPa back-pressure and non-evaporative conditions. The nozzle flow characteristics, including cavitation modelled by a Homogeneous Relaxation Model (HRM), are accounted for in the spray performance by means of a Sigma - Y model. The code is validated via two reference nozzles, the so called "Spray A" of the Engine Combustion Network plus a second nozzle from a production injector, and then extended to the eccentric geometries. The results and discussions include spray angle and penetration, air entrainment and flow parameters of the nozzle inner conditions versus the eccentricity value.

[EN] Post-injection fuel dribble is known to lead to incomplete atomisation and combustion due to the release of slow-moving, and often surface-bound, liquid fuel after the end of injection. This can have a negative effect on engine emissions, performance and injector durability. To better quantify this phenomenon, we developed an image-processing approach to measure the volume of ligaments produced during the end of injection. We applied our processing approach to an Engine Combustion Network 'Spray B' 3-hole injector, using datasets from 220 injections generated by different research groups, to decouple the effect of gas temperature and pressure on the fuel dribble process. High-speed X-ray phase-contrast images obtained at room temperature conditions (297 K) at the Advanced Photon Source at Argonne National Laboratory, together with diffused back-illumination images captured at a wide range of temperature conditions (293-900 K) by CMT Motores Termicos were analysed and compared quantitatively. We found a good agreement between image sets obtained by Argonne National Laboratory and CMT Motores Termicos using different imaging techniques. The maximum dribble volume within the field of view of the imaging system and the mean rate of fuel dribble were considered as characteristic parameters of the fuel dribble process. Analysis showed that the absolute mean dribble rate increases with temperature when injection pressure is higher than 1000 bar and slightly decreases at high injection pressures (>500 bar) when temperature is close to 293 K. Larger maximum volumes of the fuel dribble were observed at lower gas temperatures (similar to 473 K) and low gas pressures (<30 bar), with a slight dependence on injection pressure.

[ES] Halon1301 se ha utilizado como agente de extinción de incendios en sistemas activos de extinción de incendios en motores de aviones, APU (Unidad de potencia auxiliar) y protección contra incendios de carga durante más de 50 años. En 1987, una investigación realizada por el Protocolo de Montreal muestra que Halon está dañando el medio ambiente debido a sus propiedades que agotan el ozono. Por lo tanto, el uso de gases de halón ha sido prohibido en la industria por el protocolo de Montreal (1994) y Kyoto (1998). Por lo tanto, es el reemplazo de gases de halón lo que es más ecológico. Entre estas alternativas, Novec-1230 es una alternativa sostenible que funciona de manera rápida, limpia y eficiente. El sistema de extinción de incendios requiere que se diluya una concentración específica del agente de extinción de incendios (4-6% para Novec-1230 y 5% para Halon) en el aire para extinguir el fuego. El problema de cambiar la fase de la niebla rápidamente despresurizada de un sistema de extinción de incendios es un tema de gran interés debido al efecto del modelado de estos fenómenos en una simulación exitosa para diseñar estas modificaciones. Debido a la gran diferencia de presiones entre el recipiente y el ambiente, se espera que la descarga a través de la boquilla sea crítica. En este informe, se utilizan dos agentes de supresión de incendios alternativos diferentes y dos boquillas: agua y Novec1230. El objetivo principal de este proyecto es desarrollar un nuevo modelo de subcuadrícula para un U-RANS CFD Euleriano-Euleriano de dos fases que pueda usarse para reducir el costo computacional y aumentar la precisión de los enfoques tradicionales basados en Eulerian-Lagrangian. Estos dos enfoques se realizan con el software comercial CFD (ANSYS Fluent). Como validación, los rendimientos de pulverización como la forma de pulverización, el ángulo del cono de pulverización se comparan con los resultados experimentales., [EN] Halon1301 has been used as a fire suppression agent in active fire extinction systems in aircraft engines, APU (Auxiliary Power Unit) and cargo fire protection for more than 50 years. In 1987, a research carried out by the Montreal Protocol shows that Halon is damaging the environment because of its ozone-depleting properties. Therefore, the use of Halon gases has been banned in the industry by the Montreal (1994) and Kyoto (1998) protocol. So, it is indeed to find replacement of halon gases which is more eco friendly. Among these alternatives, Novec-1230 is a sustainable alternative that works quickly, cleanly and efficiently. The fire suppression system requires a specific concentration of the fire suppression agent (4-6 % for Novec-1230 and 5% for Halon) to be diluted in the air to extinguish the fire. The problem of changing the phase of the rapidly depressurized mist of a fire suppression system is a topic of high interest due to the effect of the modelling of these phenomena in a successful simulation to design these modifications. Due to the high difference of pressures between the container and the ambient, the discharge through the nozzle is expected to be critical. In this report, two different alternative fire suppression agents and two nozzles are used - Water and Novec1230. The main goal of this project is to develop a new sub-grid model for a two-phase Eulerian-Eulerian CFD U-RANS that can be used to reduce the computational cost and increase the accuracy of traditional approaches based on Eulerian-Lagrangian. These two approaches are performed with CFD commercial software (ANSYS Fluent). As validation, spray performances such as spray shape, spray cone angle are compared with experimental results.

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419882500., [EN] Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the sigma -Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier-Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.

A laser 2-focus velocimeter (L2F) has been applied for measurements of velocity and size of droplets in diesel sprays. The maximum data acquisition rate of 15 MHz has been achieved by using FPGA in order to capture every droplet which appears in the micro-scale measurement volume. A method of evaluating the mass flow rate of droplets was proposed, and the distance between droplets was adopted as an indicator of the number density of droplets and the heterogeneous structure of sprays. The diesel fuel spray was injected intermittently into the atmosphere by using a 5-hole injector nozzle. The orifice diameter of the injector nozzle was 0.113 mm, and the injection pressure was set at 40MPa by using a common rail system. Measurements were conducted in the spray on 10 planes from 5 to 25 mm downstream from the nozzle exit. It was shown that the velocity of droplet was the highest at the spray center and decreased towards the spray periphery. The size of droplet at the spray center decreased downstream and that at spray periphery increased downstream. The mass flow rate near the spray center was larger than that in the spray periphery region. It was confirmed that the fuel mass per injection evaluated by the proposed method based on the L2F measurement was nearly equal to the injected mass in a plane further than 15 mm from the nozzle exit. The probability density of droplet with a distance shorter than 5 m to the adjacent droplet increased remarkably near the spray center 5 and 12 mm downstream from the nozzle exit. It is thought that a region of high number density of droplet exists at the spray center near the spray tip when the spray penetration is shorter than 15 mm., 5th Bangladesh Society of Mechanical Engineers (BSME) International Conference on Thermal Engineering, ICTE 2012; Dhaka; Bangladesh; 21 December 2012 through 23 December 2012, identifier:Procedia Engineering, 56, pp.18-28; 2013

Accurate prediction of the discharge coefficient (C-D) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the C(D)of IMTF atomizers are unavailable. This work presents an experimental study on C-D for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (Delta p(mix)/p(amb)), the orifice length-to-diameter ratio (L-o/d(o)), and the liquid viscosity (mu(L)). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that C-D is governed mainly by GLR, and reduces if GLR, L-o/d(o), or mu(L)is increased. An increase in Delta p(mix)/p(amb)causes a C-D reduction up to Delta p(mix)/p(amb)= 0.98, and C-D increases for a higher Delta p(mix)/p(amb). Surprisingly, differences in C-D amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general C-D correlation fitting with an R-2 >= 0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.

Accurate prediction of the discharge coefficient (C-D) for internal-mixing twin-fluid (IMTF) atomizers is challenging, the effect of control factors remains inadequately understood, and comparative data on the C(D)of IMTF atomizers are unavailable. This work presents an experimental study on C-D for different IMTF atomizers with a wide range of factors, including the gas-to-liquid ratio (GLR), the inlet-overpressure ratio (Delta p(mix)/p(amb)), the orifice length-to-diameter ratio (L-o/d(o)), and the liquid viscosity (mu(L)). Five atomizers with different internal-mixing principles were probed on a cold test rig, including the frequently studied outside-in-gas (OIG) and inside-out-gas (IOG) effervescent types, the recently-introduced outside-in-liquid (OIL) and air-core-liquid-ring (ACLR) atomizers, and our new design named the swirling-air-core-liquid-ring (SACLR) atomizer. The results demonstrate that C-D is governed mainly by GLR, and reduces if GLR, L-o/d(o), or mu(L)is increased. An increase in Delta p(mix)/p(amb)causes a C-D reduction up to Delta p(mix)/p(amb)= 0.98, and C-D increases for a higher Delta p(mix)/p(amb). Surprisingly, differences in C-D amid examined atomizers were found negligible, although the flow visualization inside the orifice showed a significantly different flow character for each one of the atomizers. Finally, a general C-D correlation fitting with an R-2 >= 0.99 for all the tested nozzles was proposed. The results amend the present knowledge, allow design optimization, and provide flow rate prediction for a variety of IMTF atomizers.

The thermal usage of liquid fuels implies their combustion, which is a process strongly influenced by the performance of the atomizer, which disrupts the fuel into drops of the required sizes. The spray quality of the twin-fluid atomizers with internal mixing (IM-TFA) is primarily influenced by the two-phase flow pattern inside the mixing chamber. We studied the performance of the four types of the IM-TFA nozzles by the optical diffraction system (Malvern Spraytec) to answer the question of how the mixing chamber design influences the spray quality at low atomizing gas consumption. We tested the effervescent atomizer in outside-in-liquid (OIL) and outside-in-gas (OIG) configurations, the Y-jet nozzle and new nozzle design, and the CFT atomizer when spraying model liquids with the viscosities comparable to the common fuels (mu=60and143mPa center dot s). We found that the effervescent atomizer performance was strongly influenced by the configuration of the inlet ports. Although the OIL configuration provided the best spray quality (D32= 72 mu m), with the highest efficiency (0.16%), the OIG nozzle was characterized by unstable work and poor spray quality. Both the devices were sensitive to liquid viscosity. The Y-jet nozzle provided a stable performance over the liquid viscosity spectrum, but the spray quality and efficiency were lower than for the OIL nozzle. Our findings can be used to improve the performance of the common IM-TFA types or to design new atomizers. The results also provide an overview of the tested atomizers' performances over the wide range of working conditions and, thus, help to define the application potential of the tested nozzle designs.

Plain-jet airblast atomizers are widely used in industrial applications. The literature contains numerous papers on Sauter mean diameter, however, there is no estimation method available for spray cone angle, SCA, which derivation is the primary goal of this study. Four distinct, practical model liquids were analyzed: distilled water, diesel oil, light heating oil, and crude rapeseed oil. The atomizing pressure and liquid preheating temperature were varied in the range of 0.3–2.4 bar and 25–85 °C, respectively. This latter parameter enabled a wide and continuous liquid kinematic viscosity investigation range of 0.33–44.2 mm2/s. The resulting sprays were imaged at various shutter speeds for proper edge detection. An adaptive thresholding algorithm was developed in Matlab software environment to calculate SCA. The methodology is discussed in detail to facilitate the re-implementation of this technique since there is no generally accepted method for SCA measurement. SCA inversely varied with liquid density and followed a power law with the air-to-liquid mass flow ratio; however, the derived expression also performed well by replacing air-to-liquid mass flow ratio by either Mach number or momentum flux ratio. A simple empirical equation was derived, which allows the estimation of SCA of airblast atomization in a wide parameter range within a 3.5% deviation. The measured results were evaluated in the light of high-speed camera images in the vicinity of the nozzle; it was found that increased liquid jet breakup length decreases SCA while intense ligament formation increases it.

Plain-jet airblast atomizers are widely used in industrial applications. The literature contains numerous papers on Sauter mean diameter, however, there is no estimation method available for spray cone angle, SCA, which derivation is the primary goal of this study. Four distinct, practical model liquids were analyzed: distilled water, diesel oil, light heating oil, and crude rapeseed oil. The atomizing pressure and liquid preheating temperature were varied in the range of 0.3–2.4 bar and 25–85 °C, respectively. This latter parameter enabled a wide and continuous liquid kinematic viscosity investigation range of 0.33–44.2 mm2/s. The resulting sprays were imaged at various shutter speeds for proper edge detection. An adaptive thresholding algorithm was developed in Matlab software environment to calculate SCA. The methodology is discussed in detail to facilitate the re-implementation of this technique since there is no generally accepted method for SCA measurement. SCA inversely varied with liquid density and followed a power law with the air-to-liquid mass flow ratio; however, the derived expression also performed well by replacing air-to-liquid mass flow ratio by either Mach number or momentum flux ratio. A simple empirical equation was derived, which allows the estimation of SCA of airblast atomization in a wide parameter range within a 3.5% deviation. The measured results were evaluated in the light of high-speed camera images in the vicinity of the nozzle; it was found that increased liquid jet breakup length decreases SCA while intense ligament formation increases it.

The thermal usage of liquid fuels implies their combustion, which is a process strongly influenced by the performance of the atomizer, which disrupts the fuel into drops of the required sizes. The spray quality of the twin-fluid atomizers with internal mixing (IM-TFA) is primarily influenced by the two-phase flow pattern inside the mixing chamber. We studied the performance of the four types of the IM-TFA nozzles by the optical diffraction system (Malvern Spraytec) to answer the question of how the mixing chamber design influences the spray quality at low atomizing gas consumption. We tested the effervescent atomizer in outside-in-liquid (OIL) and outside-in-gas (OIG) configurations, the Y-jet nozzle and new nozzle design, and the CFT atomizer when spraying model liquids with the viscosities comparable to the common fuels (mu=60and143mPa center dot s). We found that the effervescent atomizer performance was strongly influenced by the configuration of the inlet ports. Although the OIL configuration provided the best spray quality (D32= 72 mu m), with the highest efficiency (0.16%), the OIG nozzle was characterized by unstable work and poor spray quality. Both the devices were sensitive to liquid viscosity. The Y-jet nozzle provided a stable performance over the liquid viscosity spectrum, but the spray quality and efficiency were lower than for the OIL nozzle. Our findings can be used to improve the performance of the common IM-TFA types or to design new atomizers. The results also provide an overview of the tested atomizers' performances over the wide range of working conditions and, thus, help to define the application potential of the tested nozzle designs.

High pressure injection systems have essential roles in realizing highly controllable fuel injections in internal combustion engines. The primary atomization processes in the near field of the spray, and even inside the injector, determine the subsequent spray development with a considerable impact on the combustion and pollutant formation. Therefore, the processes should be understood as much as possible; for instance, to develop mathematical and numerical models. However, the experimental difficulties are extremely high, especially near the injector nozzle or inside the nozzle, due to the very small geometrical scales, the highly concentrated optical dense spray processes and the high speed and drastic transient nature of the spray. In this study, several unique and partly recently developed techniques are applied for detailed measurements on the flow inside the nozzle and the spray development very near the nozzle. As far as possible, the same three-hole injector for high pressure diesel injection is used to utilize and compare different measurement approaches. In a comprehensive section, the approach is taken to discuss the measurement results in comparison. It is possible to combine the observations within and outside the injector and to discuss the entire spray development processes for high pressure diesel sprays. This allows one to confirm theories and to provide detailed and, in parts, even quantitative data for the validation of numerical models.

Spiral nozzles are widely used in wet scrubbers to form an appropriate spray pattern to capture the polluting gas/particulate matterwith the highest possible efficiency. Despite this fact, and a fact that it is a nozzle with a very atypical spray pattern (a full cone consisting of three concentric hollow cones), very limited amount of studies have been done so far on characterization of this type of nozzle. This work reports preliminary results on the spray characteristics of a spiral nozzle used for gas absorption processes. First, we experimentally measured the pressure impact footprint of the spray generated. Then effective spray angles were evaluated from the photographs of the spray and using the pressure impact footprint records via Archimedean spiral equation. Using the classical photography, areas of primary and secondary atomization were determined together with the droplet size distribution, which were further approximated using selected distribution functions. Radial and tangential spray velocity of droplets were assessed using the laser Doppler anemometry. The results show atypical behavior compared to different types of nozzles. In the investigated measurement range, the droplet-size distribution showed higher droplet diameters (about 1 mm) compared to, for example, air assisted atomizers. It was similar for the radial velocity, which was conversely lower (max velocity of about 8 m/s) compared to, for example, effervescent atomizers, which can produce droplets with a velocity of tens to hundreds m/s. On the contrary, spray angle ranged from 58 degrees and 111 degrees for the inner small and large cone, respectively, to 152 degrees for the upper cone, and in the measured range was independent of the inlet pressure of liquid at the nozzle orifice.

A scaled transparent modular model of pressure-swirl (PS) atomizer was prepared from cast PMMA (Poly(methyl methacrylate), Perspex™, Plexiglas™) with the aim to achieve a better understanding of internal flow and subsequent spray formation. Because of use of high-speed imaging and Laser Doppler Anemometry (LDA) the working liquid had to be selected with respect of a refractive index matching (RIM) with the atomizer material. The liquid should be colourless and chemically non-aggressive to the model material with suitable viscosity to achieve the Reynolds number of the internal flow of the original atomizer. Froude number should be high enough to neglect the influence of gravity on the flow. An extensive search for transparent liquids and materials of enlarged models was made with a focus on RIM in performed experiments. Several liquids were chosen, and their chemical effect on PMMA was tested. Despite the successful tests that proved the liquid suit the case, the model material was damaged and the tests proved to be insufficient. For this reason, the tests were modified to better involve the stress of the bolted model. It turned out that a force effect (bolt in the thread, pre-stressed bolt connection) on the material has a significant influence on the acceleration of the chemical effect. The internal flow was examined using a high-speed camera with several liquids.

Evaporative cooling mist spray is a cost effective solution for many cooling applications. Selection of misting spray nozzle play a major role in order to provide the suitable spraying condition in regards to the application. One of the most widely use mist spray application is evaporative cooling of outdoor open area. This study was carried out to characterized the spray formation, size of droplet, velocity of the droplet and the angle of the spray formation from a commercial mist spray nozzle namely 1/8 SF-CE SM nozzle with 1 mm and 2 mm diameter hole. Water was supplied with different pressure of 1, 2 and 4 bar. High speed video camera and still digital camera using short burst of flash were used to produce the video and image for analysis. The results show that increase in water pressure affect the spray angle, increase droplet speed and decrease droplet size of the mist spray.

The conducted study investigates the potential of a newly released multi-phase solver to simulate atomization in liquid rocket injectors. The "VOF-to-DPM" solver was used to simulate primary and secondary atomization in an air-blast atomizer with a coaxial injector-like geometry. The solver uses a hybrid Eulerian/Eulerian-Lagrangian formulation with a geometric transition criteria between the two models. The conducted study assumed isothermal, non-reacting flow at room temperature. The primary focus was predicting Sauter Mean Diameter and droplet velocity data at a sampling plane downstream of the injection site. The results showed that the solver is able to produce the expected data and to predict trends similar to those found in experimental measurements. The accuracy of the produced droplet diameters was roughly a factor 2 off compared to experiment. This is attributed to mesh resolution. Measurements were obtained via a cooperative agreement between TU Delft and The University of Sydney. It was concluded that the solver has the potential to predict atomization at a reasonable computational cost, but further study is needed to confirm its full capabilities., Aerospace Engineering