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Effects of n-butanol on the combustion process in a direct injection spark ignition engine were investigated through flame visualization and spectroscopy. An optically accessible engine was equipped for the trials with a commercial cylinder head and wall guided injection system. Injection pressure (100 bar) and engine speed (2000 rpm) were fixed while injection timing and duration were changed to realise stoichiometric and lean fuelling in homogenous charge conditions. Specifically, UV-visible digital imaging was applied in order to study the flame front inception and propagation with particular interest in the early combustion stages. UV-visible natural emission spectroscopy was applied to investigate the formation and the evolution of the main chemical compounds characterizing the spark ignition and combustion processes. Detailed image processing allowed to correlate the morphology and the local flame front curvature with thermodynamic data. Overall engine operation was found to be roughly the same for the both fuels, with butanol providing a slight decrease of performance and a significant reduction of NOx and soot emissions compared to gasoline. Injection phasing resulted a key point to enjoy the alternative fuel benefits. Regarding flame wrinkling, flame distortion and width of the probability density function (PDF) decreased at increasing peak pressure. Butanol flames were slightly more wrinkled than those for gasoline. The effect of fuel type on the PDF mean value was negligible

Ice crystals ingested by a jet engine at high altitude can partially melt and then accrete within the forward stages of the compressor, potentially causing performance loss, damage and/or flameout. Recent research into this ice crystal icing (ICI) phenomenon conducted at the National Research Council of Canada suggests that the liquid water content vliq of an accretion significantly affects the accretion's susceptibility to erosion by ice crystals, and therefore accretion growth. This paper describes the development and application of an instrument for measuring vliq, potentially providing a method for correlating erosion behavior (e.g. as ductile or brittle) and properties. The instrument measures the complex admittance Y* of a mixed-phase deposit bridging a pair of electrodes, which is modeled as a resistor and capacitor in parallel, and calculates the deposit's relative permittivity εr from the capacitance. Experiments and electrostatic simulations were conducted to correlate εr as a function of vliq for vliq up to ∼40%, using calorimetry to determine vliq. These measurements were made at an excitation frequency of 2MHz, where the relative permittivities of ice and liquid water are insensitive to change of frequency. The paper also describes icing tests where the instrument was used to measure vliq as a function of freestream liquid-to-total water content (LWC/TWC) for two test articles, a cone and a forward-facing cup. The measurements show that vliq lies in the range 25-33% when LWC/TWC is in the range giving worst accretion (LWC/TWC∼10-20%). The instrument is also used to measure thickness growth rate for the cup., SAE 2015 International Conference on Icing of Aircraft, Engines, and Structures, June 22-25, 2015, Prague, Czech Republic

Prediction of spray droplet temperature is routinely performed within automotive engineering CFD simulation. Important applications include fuel spray modelling for in-cylinder combustion studies and urea-water spray modelling for SCR aftertreatment studies. Transient droplet surface temperature strongly influences droplet and spray evaporation rate and subsequent system performance. In this paper, different droplet temperature models are presented and compared for both single droplet modelling and a single-hole Lagrangian spray CFD simulation in OpenFOAM. The aim is to determine the complexity of implementation of the models and their effect on prediction accuracy for droplet surface temperature, evaporation rate and lifetime. A non-ideal multi-component droplet evaporation model using UNIFAC and NRTL for activity coefficient calculation is used. Model gasoline fuels containing varying quantities of ethanol are studied at conditions appropriate to gasoline direct injection. Three droplet temperature models are compared: a lumped thermal model typically employed in CFD packages; an effective thermal conductivity model (ETC) using the full heat equation; and an ETC model tracking the surface and centre temperature only. For droplet simulations, discrepancies of up to 13% in calculated droplet lifetime are found between the lumped thermal model and the effective conductivity models. The greatest discrepancy in lifetime is observed at conditions and compositions where rapid liquid thermal transients are encountered. This effect is characterized for the first time using the wet-bulb temperature, initial liquid temperature and fuel ethanol content, to guide modellers to an appropriate temperature model for the level of accuracy desired. The effect of droplet temperature modelling in spray CFD simulation is smaller, as measured by maximum changes in spray penetration (2%), evaporation rate (2%) and Sauter Mean Diameter (1.2%). A non-uniform temperature model is required when significant transient temperature change is expected, near-nozzle spray is studied or sub-models such as droplet collision and break-up are not in use.

[EN] Low pressure exhaust gases recirculation (LP-EGR) is becoming a state-of-the-art technique for Nitrogen oxides (NOx) reduction in compression ignited (CI) engines. However, despite the pollutant reduction benefits, LP-EGR suffers from strong non-linearities and delays which are difficult to handle, resulting in reduced engine performance under certain conditions. Measurement and observation of oxygen concentration at the intake have been a research topic over the past few years, and it may be critical for transition phases (from low pressure to high pressure EGR). Here, an adequate selection of models and sensors is essential to obtain a precise and fast measurement for control purposes. The present paper analyses different sensor configurations, with oxygen concentration measurements at the intake and exhaust manifold and combines observation techniques with sensor models to determine the potential of each configuration. Experimental results from a 2.2 l. diesel engine are used to validate the presented techniques.

The use of methane as supplement to liquid fuel is one of the solution proposed for the reduction of the internal combustion engine pollutant emissions. Its intrinsic properties as the high knocking resistance and the low carbon content makes methane the most promising clean fuel. The dual fuel combustion mode allows improving the methane combustion acting mainly on the methane slow burning velocity and allowing lean burn combustion mode. An experimental investigation was carried out to study the methane-gasoline dual fuel combustion. Methane was injected in combustion chamber (DI fuel) while gasoline was injected in the intake manifold (PFI fuel). The measurements were carried out in an optically accessible small single-cylinder four-stroke engine. It was equipped with the cylinder head of a commercial 250 cc motorcycles engine representative of the most popular two-wheel vehicles in Europe. UV-visible spectroscopy measurements were performed to analyze the combustion process with high spatial and temporal resolution. In particular, UV-visible spectroscopy allows detecting the chemical markers of combustion process such as the radicals OH* and CH*. The in-cylinder lambda spatial and temporal evolution was evaluated. The combustion evolution is characterized by means of a high speed cycle resolved camera. The exhaust emissions were characterized by means of gaseous analyzers. The measurements were performed under steady state conditions at different engine operating conditions.

In recent years, several studies on the efficiency of modern diesel engines have focused on the modeling of combustion process in its different phases. Here, analytical equations are used to describe the physical phenomena that occur in the cylinder. The good agreement between the experimental and simulated data could improve the predictive capabilities of the computational code and reduce the cost of experimental activities. For the modeling of a diesel spray, the first step has been to investigate its behavior in a non-combusting environment; in particular, Musculus and Kattke proposed a model for the simulation of the injection of fuel in non-reacting still environment. Starting from that knowledge, the authors apply the injection model to a compression ignition research engine. By means of an optical engine, injection phase has been investigated via 2D digital imaging. The main jet characteristics like penetration and dispersion angle have been measured. The penetration data were compared with those provided by the 1D model with the same in-cylinder conditions. Some differences have been noted. In order to match the experimental data with the predicted ones: dispersion angle, ramp-up of injection rate, and the equivalence ratio curve need to be modified.

As is known, internal combustion engines based on Otto or Diesel cycles cannot complete the expansion process of the gas inside the cylinder, thus losing a relevant energy content, in the order of 30% of total. The residual energy of the unexpanded gas has been partially exploited through the use of an exhaust gas turbine for turbocharging the internal combustion engine; further attempts have been made with several compound solutions, with an electric generator connected to the turbocharger allowing to convert into electrical energy the quota power produced by the turbine which is not used by the compressor, or with a second turbine downstream the first to increase the exhaust gas energy recovery. Turbo-compound solutions were also employed in large marine Diesel engines, where the second turbine downstream the first was used to deliver more power to the main propeller shaft. In all these cases the overall efficiency increments remained within 5%. If completely recovered by the use of a properly designed expander-generator unit, the energy content of the unexpanded in-cylinder gas could substantially increase the overall efficiency of the thermal unit. In the present paper the authors evaluate, by means of simple yet effective calculations, the efficiency attainable by a thermal unit composed of a spark ignition engine endowed of an exhaust gas energy recovery expander connected to a proper generator. The proposed thermal unit, which is particularly suitable for hybrid propulsion solutions, has been evaluated both in the naturally aspirated and in the supercharged version. The efficiency of each thermal unit is also compared to reference baseline engine, thus highlighting the real benefit introduced by the adoption of the proposed thermal unit. As result, it was found that the complete and efficient recovery of the unexpanded gas energy has the potential to increase the overall efficiency of the propulsion system by 10-15%, depending on the characteristics of the thermal engine and of the exhaust energy expander-generator unit.

Scientists and technologists attracted towards natural fibers like banana, cotton, coir, sisal, hemp and jute for the application civil structures and consumer goods. It was identified the electrical resistance, thermal and acoustic insulating properties for possessing of these natural fibers in composites. Natural fibers have many benefits compared to artificial fibers, as an example less density, less weight; low cost, specific properties and they are recyclable and biodegradable. There aren’t any skin effects because of high strength and stiffness, renewable. In alternative manner, there also are some limitations, as an example less thermal stability and wetness uptake. several of them studied a major improvement in properties of hybrid composites with reinforced with glass fiber in resin content however it’s naturally hazard with usage of this glass fiber content. There are many publications on review of fiber reinforced composites, a notable research has been done on natural fiber polymer composites but research on jute, hemp, hybrid of jute fiber and hemp fiber, hybrid (jute/hemp) fiber with SiC particulates as filler at specific extent fractions primarily.In this paper, hybrid (hemp and jute) fiber reinforced epoxy matrix composites were fabricated by using hand lay-up technique of different weight percentage of hybrid fiber and SiC particulates as filler have been studied and their thermal properties such as density, Thermal gravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) by which we can know thermal stability of the composites.

When we see a tangible creation and our inquisitive nature crave to have touch and feel of the same, many questions hover our mind like what it is, what does it do and how it was made. All man-made creations which first get conceived in human mind pass through several processes and evaluation in order to be eventually ready for usage and application. The evaluation and reviews are required so that the final product which is a part of the creation, functions the same as it was intended to do. The analysis which could be limited to part level or system level gives us a foresight into any possibility of pre-production or pre-release failures which might be barriers in the success of the product. Tolerance stack up is one of such analysis approaches used today in product design to understand how imperfections in parts as they are manufactured, and later assembled as products, affect its capability to meet customer requirements. Tolerance stack helps engineers to study any accumulated variation in parts in a product assembly. It is a way of understanding how sources of variation in part dimensions and assembly constraints propagate across parts and assemblies, and how this variation affects meeting the design requirements within process capability of manufacturing organizations. We get these dimensions and tolerances from the engineering drawings. If we consider the most common techniques used for tolerance stack analysis like Worst Case method (WC) and RSS method (Root-Sum-Squared), they have limitations in attending complex architectures, allowing flexibility to designers and cost. CETOL 6 Sigma utilizes a method called Method of System Moments which disregards these limitations. An example of this approach utilizing CETOL 6σ software application will be presented in this paper.

Fundamental frequency determination can help us to find where the resonance will happen. The need of dynamics characteristic is one of the major concerns to find the natural frequency. This paper aims to find the natural frequency of a laminated composite plate and optimizing the plate to get maximum frequency. Finding the optimum design by experimentally are more expensive. To avoid the complications now a days the researchers are using computational method. The present work offering an approach to design optimization of a composite plate with FEA tool and to achieve different combinations of objective using Design of Experiment (DOE) and the maximization of the fundamental natural frequency by using ANSYS Design explorer.

It is of critical importance to understand the failure behavior of Lithium-ion batteries subjected to mechanical loading order to improve crash safety of electric vehicles. The deformation of battery pack during collision/crash results in catastrophic events and thus it becomes necessary to study the failure of the battery during such scenarios. The goal of this research was to understand the mechanical and electrical failure characteristics of cylindrical Lithium-ion cells subjected to deformation. This paper discusses on experimental investigations on material failure in the electrode assemblies i.e. the jellyroll of Li-ion batteries after mechanical loading which eventually leads to electrical failure, short circuit and at times violent thermal runaway scenarios. Experiments were carried out on NCA chemistry 18650 cylindrical cells under various loading conditions in a custom designed fumehood which capture the various failure modes of the cell in a module or a battery pack in crash events. The loading conditions include, compression between two flat plates in horizontal and vertical terminals orientations, lateral indentation by a cylindrical rod, hemispherical punch, flat circular punch and three-point bending. The understanding of mechanical abuse induced short circuit behavior of Li-ion cells will aid in further development of battery crash models thereby optimizing battery pack development cycle for xEV applications.

In this paper, the study of plastic bonded magnetic material is studied for the surface adhesion of the material on to the surface of a metal cup. The bonded magnetic material is formed as a mixture of plastic material blended with ferrite or NdFeB Magnetic powder. The amount of magnetic material used is confined to the magnetic property of the magnetic powder that can exhibit the required magnetic performance as higher rotational speed and higher temperature. The magnet is injection moulded onto the outer circumference of the metal cup. The magnet is bonded onto the metal surface which is of cup shape and this assembly is magnetized to form a multipole magnet. This multipole magnet is designed to withstand high centrifugal force during the magnet rotation at higher rpm say 40000 rpm. For improving the adhesion properties with the two dissimilar material, the plastic bonded magnetic material and metal cup with zinc plating, the design on the metal cup is probed in detail and simulation has been carried out using FEA software. The adhesion of this two material binding is to be confined and confined to the properties of the plastic material in the mixture of the plastic bonded magnetic material.

Use of Supercapacitor with Li-ion Battery as an Energy Storage System (ESS) for a two wheeler can be implemented in a variety of configurations with the aim to improve the cycle life of Li-ion batteries by decreasing the current transients they are subjected to, and to increase the peak power capability of the Power pack. MATLAB/SIMULINK tool is used as simulation software to model the Road Profile, Vehicle, Electric Powertrain and the Hybrid ESS (HESS). In this paper, the effect of different topologies of HESS and effect of degree of hybridization is analyzed w.r.t. current profile, voltage profile and State of Charge (SOC). Results show that use of HESS for Electric two wheeler in place of battery decreases the Peak/RMS Current experienced by the battery with corresponding improvement in battery life.

In this paper the heat transfer coefficient and the heat transfer rate of a heat exchanger is scrutinized by using nanofluids. The silicon carbide nanoparticles, milled and sonificated as nanofluids of volume fractions 0.01499(%) and 0.01399(%). The heat transfer characteristics of SiC(P)/water, SiC(M)/water, SiC(P)/EG, SiC(M)/EG are measured in a concentric tube heat exchanger under laminar flow condition. The consequence of nanoparticle physiognomies, Reynolds number, on the heat transfer characteristic is scrutinized. It has been found that the addition of milled nanoparticlein the base fluids enhances the heat transfer characteristics rather than the normal nanoparticle. The experimental results shows that the heat transfer characteristics of SiC(M) is higher than that of SiC(P) in both the case of water and EG. This is because of the structural changes of SiC-M by the deformation caused by the ball milling.

Automakers are being subjected to increasingly strict fuel economy requirements which led OEMs to focus more on Light weighting and Energy efficiency areas. Considering the aforesaid challenges, efforts have been taken in Light weighting of mounting bracket for Engine application.This paper deals with conversion of Engine accessory bracket from Aluminum material to Metal Matrix composite (MMC). In Design phase, existing bracket has been studied for its structural requirements and further Bracket is designed to meet MMC process requirement and CAE carried out for topology optimization and Structural integrity. Finally observations and results were compared for Existing design and Proposed design and further optimization proposed.

The use of piezoelectric cylinder pressure sensors is very popular during engine testing, but cylinder pressure information is becoming mandatory also in several on-board applications, where Low Temperature Combustion (LTC) approaches require a feedback control of combustion, due to poor combustion stability and the risk of knock or misfire. Several manufacturers showed the capability to develop solutions for cylinder pressure sensing in on-board automotive and aeronautical applications, and some of them have been patented. The most straight-forward approach seems the application of a piezo-electric washer as a replacement of the original part equipping the spark plug; the injector could also be used to transfer the cylinder pressure information to the piezoelectric quartz, in diesel or Gasoline Direct Injections (GDI) engines. The paper describes the features of signals acquired using piezoelectric washers, discussing possible applications, highlighting the factors which impact the sensors accuracy, and proposing algorithms to compensate potential errors in the evaluation of combustion metrics. The sensors have been first tested on a press, then in two different gasoline engines: a naturally aspirated V12 and a turbocharged 2 cylinders with Variable Valve Lift system (VVL). Signals have been compared to those obtained with lab-grade cylinder pressure sensors, with particular attention to peak pressure, combustion phase and knock intensity. The main issue affecting the accuracy of cylinder pressure measurement using the piezoelectric spark plug washer is the effect of temperature variations both on the force transmitted by the thread to the washer and piezoelectricity properties.

Butanol is an attractive alternative fuel by virtue of its renewable source and low sooting tendency. In this paper, three butanol isomers (n-butanol, isobutanol, and tert-butanol) were induced via port injection respectively and n-heptane was directly injected into the cylinder to investigate reactivity controlled compression ignition in a heavy-duty diesel engine. This work evaluates the potential of applying butanol as low reactivity fuel and the effects of reactivity gradient on combustion and emission characteristics. The experiments were performed from low load to medium-high load. Due to the different reactivities among the butanol isomers, the exhaust gas recirculation rate and the direct injection strategy were varied for a specific butanol isomer and testing load. Particularly, isobutanol/n-heptane can be operated with single direct injection and no exhaust gas recirculation up to medium load due to the high octane rating. As the load increases, all three butanol isomers displayed increased peak cylinder pressure and pressure rise rate. Especially, n-butanol cases yielded a pressure rise rate of 23.4 bar/oCA at medium-high load because of sub-optimal combustion phasing. It constrains the high load limit of n-butanol/n-heptane operation. While tert-butanol cases presented the slowest heat release rate and consequently the lowest pressure rise rates. Extremely low NOx emissions were achieved for all three isomers. Interestingly, tert-butanol/n-heptane operation stands out for showing ignorable engine-out soot mass in the whole testing range. N-butanol cases require the most direct fueling to phasing the combustion properly and displayed the highest soot mass and the highest number of particles in the accumulation mode. Among the isomers, tert-butanol/n-heptane operation achieved the highest gross indicated efficiency (above 52%) in most operating loads.

Diesel engine has fuel combustion capability in various high density oil such as residual fuels or biofuels derived from fossil or living matter. But for commercial use, these fuels except bio diesel fuel (BDF) should be heated, separated and filtered by equipment and dosed or mixed with additive or distillate oil etc. before being supplied to the engine in order to improve combustibility. This study aims to illuminate fuel characteristic of blend contained woody pyrolysis oil (WPO) which is high viscosity and incombustible, and dimethyl ether (DME) whose emission of combustion has no soot particle. This paper describes thermo-physical property of neat WPO and the blend on the basis of the evaluation of fuel fluidity by measurement and calculation of viscosity. According to the result, it was confirmed that the fluidity of WPO was improved by mixing DME and the approximate viscosity expressions at any temperature of WPO and the blend were good accuracy.

Optical diagnostic was applied to undiluted engine exhaust to supply a low cost and real time evaluation of the oil dilution tendency of selected fuels. Specifically, UV-visible-near IR extinction spectroscopy was applied in the exhaust line of a Euro 5 turbocharged, water cooled, DI diesel engine, equipped with a common rail injection system. The engine was fuelled with commercial B5 fuel and a B30 v/v blend of RME and ultra low sulfur diesel. The proposed experimental methodology allowed to identify the contribution to the multi-wavelength extinction of soot, fuel vapor, hydrocarbons and nitrogen oxide. Further, the evolution of each species for different post-injection interval settings was followed. On-line optical results were correlated with off-line liquid fuel absorption values. Moreover, spectroscopic measurements were linked to in-cylinder pressure related data and with HC and smoke exhaust emissions. The late post injection activation and fuel amount increase did not affect the energy release within the cylinder for either fuels. As a consequence, soot and NOx exhaust emissions remained constant during the post-injection setting. The HC exhaust increase was correlated to post-injection amount and followed in the time by UV extinction signal. The blend B30 attained a lower UV signal that was related to higher oil dilution tendency of biofuel.

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Multi-wavelength ultraviolet-visible extinction spectroscopy was applied to follow the evolution of fuel vapor injected by post-injection along the exhaust line of a common-rail turbocharged direct-injection diesel engine at moderate speed and load. The exhaust line was specifically designed and customized to allow the insertion of the optical access upstream of the Diesel Oxidation Catalyst. During the experimental campaign, the engine was fuelled with commercial B5 fuel and a B30 v/v blend of RME and ultra low sulfur diesel, monitoring emissions upstream of the catalyst and exhaust gas temperature across the catalyst. Tests were performed at different engine operating conditions with particular attention to moderate speed and load. The high temporal evolution of the UV-visible extinction measurements allowed to follow the evolution of the fuel vapor injected by post-injection during the transition from standard combustion mode to filter regeneration combustion mode, characterized by a higher amount of fuel injected into the exhaust line. Results indicate that, in some engine operating conditions, the fuel vapor formed by post-injection does not completely contribute to the oxidation process over the catalyst since a negligible increase in temperature has been recorded across the catalyst.

One promising approach to reduce pollutants from compression ignition engines is the Partially-Premixed- Combustion in which engine out emissions can be reduced by promoting mixing of fuel and air prior to auto-ignition. A great interest for a premixed combustion regime is the investigation on fuels with different reactivity by blending diesel with lower cetane number and higher volatility fuels. In fact, fuels more resistant to auto-ignition give longer ignition delay that may enhance the fuel/air mixing prior to combustion. During the ignition delay period, the fuel spray atomizes into small droplets, vaporizes and mixes with air. As the piston moves towards TDC, as soon as the mixture temperature reaches the ignition point, instantaneously some pre-mixed amount of fuel and air ignites. The balance of fuel that does not burn in premixed combustion is consumed in the ratecontrolled combustion phase, also known as diffusion combustion. Fuel composition, charge dilution, injection pressure as well as injection timing are the main factors that influence combustion and emission formation in the compression ignition engine. In order to evaluate the effects of these factors on in-cylinder spray combustion and soot formation, UV-visible digital imaging and natural emission spectroscopy were applied in a single cylinder high swirl compression ignition engine. The test engine was optical accessible and equipped with a common rail multi-jets injection system. Combustion tests were carried out using commercial diesel and a blend of 80% diesel with 20% gasoline by volume (G20). The cetane number lower than pure diesel fuel of this blend produced longer ignition delay for enhanced in-cylinder fuel/air mixing. Two injection pressures (70 and 140 MPa), several injection timings at two EGR rates were tested. UV-visible emission spectroscopy was used for detecting the chemical markers of combustion process. Chemiluminescence signals, due to OH, HCO, CO and CO2 emission bands, were identified. OH emission was correlated to NO measured at the engine exhaust. The soot spectral feature in the visible wavelength range was correlated to soot engine out emissions.

The combustion behaviour, the mechanisms of soot formation, and the emission performance of a mixture of polyoxymethylene dimethyl ethers (POMDME) oligomers with a number of oxymethylene units ranging from 3 to 5, both neat and blended at 12.5% and 50% levels with commercial diesel fuel have been investigated. The goals were a first evaluation of the POMDME impact on the diesel injector behaviour, on the combustion process as well as on the emission performance of a light duty engine. Then a brief screening on the capability to improve the NOx-PM trade-off using POMDME by means of the exhaust gas recirculation (EGR) rate increment was also assessed. Therefore, the experiments were carried out first using an injector test rig to control injection parameters, then in a transparent singlecylinder research engine with optical access for combustion visualization with spatially-resolved measurements of flame temperature and soot concentration, and finally in a light-duty multi-cylinder engine. Two operating conditions were chosen for the tests as representative of the most critical point for emission and noise optimization: engine speed of 1500 rpm and brake mean effective pressure (BMEP) of 5 bar, and 2500 rpm and 8 bar BMEP. Results from the single-cylinder engine indicate that the presence of the POMDME affects essentially the process of soot oxidation and results in a significant increase of the oxidation rate. This effect is attributed to the presence of intramolecular oxygen in the fuel which is readily available in situ and to the higher flame temperatures. The tests with the multi-cylinder engine have demonstrated that with the neat POMDME and to a lesser extent also with the 50% blend it is possible a simultaneous optimization of NOx and PM emissions and also of the noise level to a limit that could not be reached with conventional diesel fuels. For the 10-12% blend that could be used in nondedicated engines, the reduction of PM emission was about 40%, while with higher blends and EGR recalibration in dedicated vehicle fleets very low NOx exhaust emission can be reached.

Premixed combustion modes in compression ignition engines are studied as a promising solution to meet fuel economy and increasingly stringent emissions regulations. Nevertheless, PCCI combustion systems are not yet consolidated enough for practical applications. The high complexity of such combustion systems in terms of both air-fuel charge preparation and combustion process control requires the employment of robust and reliable numerical tools to provide adequate comprehension of the phenomena. Object of this work is the development and validation of suitable models to evaluate the effects of charge premixing levels in Diesel combustion. This activity was performed using the Lib-ICE code, which is a set of applications and libraries for IC engine simulations developed using the OpenFOAM® technology. In particular, a turbulence-chemistry interaction model, based on the simple Eddy Dissipation Approach, was introduced to account for the effects of turbulent mixing on chemical reaction rates. It is a tentative solution to represent the effects of sub-grid mixing on the chemical reaction rates when detailed reaction mechanisms are adopted. Chemical reaction rates were computed by a robust semi-implicit extrapolation method for integrating stiff Ordinary Differential Equations with monitoring of both local and global error to adjust stepsize. To reduce the CPU time when detailed chemistry was used, both the ISAT (in-situ adaptive tabulation) and DAC (dynamic adaptive chemistry) techniques were adopted in combination. Simulations were performed by varying the charge premixing level from the typical diesel combustion mode towards an almost completely premixed/HCCI mode using n-heptane, whose injected mass was split between portinjection and direct-injection. This allowed a detailed investigation of the “mixed injection conditions”, that are typical of dual fuel configurations without employing fuels of different chemical nature, composition and ignition tendency. The choice of using a single fuel was motivated by the need to isolate the effects of different premixing levels and the resulting interaction between the charge and the fuel spray. Measurements for validation were collected by means of specific experiments on a fully instrumented single cylinder research engine, having the injection and the combustion systems architecture typical of the current light duty diesel engine technology. To realize homogeneous air-fuel charge, the intake manifold is modified to provide the desired extent of fuel port-injection.

Optical imaging and UV-visible detection of in-cylinder combustion phenomena were made in a single cylinder optically accessed high swirl multi-jets compression ignition engine operating with two different fuels and two EGR levels. A commercial diesel fuel and a lighter fuel blend of diesel (80%) and gasoline (20%), named G20, were tested for two injection pressures (70 and 140 MPa) and injection timings in the range 11 CAD BTDC to 5 CAD ATDC. The blend G20 has a lower cetane number, is more volatile and more resistant to the auto-ignition than diesel yielding an effect on the ignition delay and on the combustion performance. Instantaneous fuel injection rate, in-cylinder combustion pressure, NOx and smoke engine out emissions were measured. Taking into account the particular configuration of the engine, the efficiency was estimated by determining the area under the working engine cycle. Moreover, it is also known that the diffusion flame lift-off length strongly influences the soot formation, which is affected by in-cylinder gas density, air swirl and jet to jet interaction. To understand the role played by these factors on lift-off length and soot formation, images of UV-VIS chemiluminescence were used to measure the diffusion flame lift-off length. The results demonstrate as the G20 fuel blend, at late injection timing and high EGR (50%), increases the ignition delay, allowing to operate, at late injection timing, in a partially premixed low temperature combustion (PPLTC) regime in which the fuel is completely injected before the start of combustion. In this regime, strong reduction of engine out emissions of smoke and NOx were obtained with a penalty on engine efficiency. This limitation was overcome operating at earlier injection timing (11 CAD BTDC) in which a mixing controlled low temperature combustion (MCC) LTC regime was realized. In this regime, a good compromise between low engine out emissions and efficiency was made possible. Finally, images of UV-VIS chemiluminescence were also used to measure the flame liftoff length, defined as the distance between the injector orifice and the most upstream location of flame chemiluminescence on the fuel jet. Flame lift-off data were plotted versus the visible emission intensity at 532 nm, representative of soot emission. It was observed that, for all engine test conditions an increase of lift-off length corresponded to a decrease of incylinder soot production.

This paper describes how the number of traffic deaths in Japan was 4,914 for the year 2009. Since the head was the most common site of injury in traffic accidents, traumatic brain injury caused the fatalities in these accidents. The objective of this paper was to quantify micro injuries in the animal brain for the purpose of gaining insight and understanding of human brain injury tolerance. In vitro stress relaxation experiments and in vivo impact experiments were conducted using porcine brain matter. The distribution of the damage ratio of the transverse to longitudinal length of cells, hereafter, referred to as an aspect ratio, in the brain matter under loading were examined in both experiments. In the in vitro stress relaxation experiments, specimens were compressed vertically with a compression velocity of 1 mm/s, and the displacement was held for 140 sec when the compression strain reached the target strain. In the experiments, there were five categories of compression strain: 10, 20, 30, 40, and 50 percent. The aspect ratio of the cell body was 1.5 or less in a no-load condition. On the other hand, the cell body was observed to be greater than 1.5 in the results from the experiments if the compression strain was 30% or more. The results from theses experiments show that a compression strain between 20% and 30% corresponds to the threshold for the extremely deformed cell at the micro level. In the in vivo impact experiments, pigs in an unconscious state were exposed through craniotomy, and their exposed brains were hit with a ram at a low speed of 3.3 m/s and a high speed of 7.2 m/s. The paper revealed that the number of cells in which the aspect ratio was greater than 1.5 increased if the impact is provided under the high speed. At the same time, the results indicated that cell deformation was dependent on the ram velocity in the brain matter. Therefore, the compression strain on the entire brain from the direction of the force applied to the brain may be one criterion for assessing brain damage.

Nowadays an elevated number of two, three and four wheels vehicles circulating in the world-wide urban areas is equipped with Port Fuel Injection Spark Ignition (PFI SI) engines. Their technological level is high, but a further optimization is still possible, especially at low engine speed and high load. To this purpose, the scientific community is now focused on deepening the understanding of thermo fluid dynamic phenomena that takes place in this kind of engine: the final purpose is to find key points for the reduction in engine specific fuel consumption and exhaust emissions without a decrease in performance. In this work, the combustion process was investigated in an optically accessible single cylinder PFI SI engine. It was equipped with the head, injection device and exhaust line of a commercial small engine for two-wheel vehicles, it had the same geometrical characteristics in terms of bore, stroke and compression ratio. The combustion chamber was optically accessible through a quartz ring under the engine head and a sapphire window on the piston top. Cycle-resolved visualization was carried out to follow the flame propagation from the spark ignition until the late combustion phase. The visualization was performed from the bottom of the engine and from the lateral side with different camera inclinations. High spatial resolution visualization of the combustion process was carried out. Moreover two color pyrometry method was applied to evaluate the spatial distribution of diffusion flames temperature and soot concentration in the combustion chamber. UV-visible emission spectroscopy was used to identify the chemical species that feature the combustion process and to study the pollutants formation. The cyclic variability and the fuel deposits formation on the combustion chamber surfaces were also investigated. All the measurements carried out in the combustion chamber were correlated with the main engine parameters and exhaust emissions. The effect of the fuel injection phasing was tested. Two fuel injection strategies were considered: in the first one, the fuel injection started when the intake valves were open; in the second one the fuel injection occurred at closed intake valves.

In this paper a numerical model is used for analysis of parameters, which affects heat pipe operation. The steady state incompressible flow are solved in Cartesian coordinates in both vapour region and wick structure, using professional CFD (Computational Fluid Dynamics) software. The objectives of this paper were to study of the parameters variation on the operation of heat pipes. The heat pipes are made from copper tube with the outer diameter 8.9 [mm] and the length 200 [mm]. The water is used as a base working fluid while the nanoparticles used in the present study are the iron oxide nanoparticles. Two cases with volume concentration 0 and 2% for iron oxide nanoparticles are considered. Fig.1. Heat pipe construction and principle of operation. In this paper, using the facilities offered by the ANSYS CFX, CFD code, the authors investigate numerically the analysis of parameters which affects heat pipe operation. The steady state incompressible flow is solved in Cartesian coordinates in both vapour region and porous media. The objective of this paper was to study of the parameters variation on the operation of the heat pipes. The heat pipes are made from copper tube with the outer diameter 8.9 [mm] and the length 200 [mm]. The water is used as a base working fluid while the nanoparticles used in the present study are the iron oxide nanoparticles. Two cases with volume concentration 0 and 2% for iron oxide nanoparticles are considered. The geometry creation, which consists of annular concentric heat pipe, through which circulates water and water vapour, were drawn as a CAD data, with the aid of a professional software – package, ACAD 2002, and imported in ANSYS Workbench environment as SAT file.

Due to titanium’s excellent strength-to-weight ratio and high corrosion resistance, titanium and its alloys have great potential to reduce energy usage in vehicles through a reduction in vehicle mass. The mass of a road vehicle is directly related to its energy consumption through inertial requirements and tire rolling resistance losses. However, when considering the manufacture of titanium automotive components, the machinability is poor, thus increasing processing cost through a trade-off between extended cycle time (labor cost) or increased tool wear (tooling cost). This fact has classified titanium as a “difficult-to-machine” material and consequently, titanium has been traditionally used for application areas having a comparatively higher end product cost such as in aerospace applications, the automotive racing segment, etc., as opposed to the consumer automotive segment. Herein, the problems associated with machining titanium are discussed, and a review of cutting tool technologies is presented that contributes to improving the machinability of titanium alloys. Additionally, nonconventional machining techniques such as High Speed Machining and Ultrasonic Machining are also reviewed. Also discussed are additional factors that need to be considered especially pertaining to the machining of titanium alloys, a crucial one being the non-conformity with standard tool wear models. Subsequently, the results of a controlled milling experiment on Ti-6Al-4V is presented, to evaluate the relationship between certain tool preparation/process parameters and tool wear for a comparison with traditional wear models. INTRODUCTION Titanium is the seventh most abundant metal and the fourth most abundant structural metal in earth’s crust behind aluminum, iron and magnesium. Titanium and its alloys are considered as alternatives in many engineering applications due to their superior properties such as retained strength at elevated temperatures, high chemical inertness and resistance to oxidation. Titanium has traditionally been utilized as a lightweight, very strong and exceedingly corrosion resistant material in the aerospace industry, electric power plants, seawater desalination plants, and heat exchanges. Also, it has been used in industrial applications such as petroleum refining, nuclear waste storage, food processing, pulp and paper plants, and marine applications [1]. Nevertheless, when considering the use of titanium as an automotive component material, there are several conflicting aspects that must be addressed. First of all, the cost of titanium is relatively high in comparison to other common engineering materials such as aluminum, magnesium, and steel. For this reason, it specifically calls for implementation and use only when extreme conditions are to be met, such as in the aerospace industry. The main reason for the increased cost is due to the limited demand from other market segments, thus making the extraction of the titanium ore expensive. Also, the processing costs for converting the ore into commercially usable titanium and its alloys is extensive and requires special processing procedures and involves vast batch production and careful process control, making them difficult to automate. Second, the difficulty in efficiently manufacturing titanium components has a significant adverse effect on processing cost which is mainly due to its low modulus of elasticity and high yield stress. Another manufacturing concern that arises during the machining of titanium is its susceptibility to work hardening during the cutting process and its tendency to react with many cutting tool materials causing substantial tool wear. Additionally, titanium has poor thermal conductivity properties, making heat dissipation a problem, again contributing to higher tool wear. Of primary concern however is the lack of material grade development outside the aerospace industry in which most of the alloys are developed for extreme conditions. This severely limits the currently available grades suited for automotive applications. Thus, a suite of lower strength alloys with properties specially catered for commercial automotive use needs to be developed. This paper examines most of the issues traditionally associated with the machinability of titanium and titanium alloys. As mentioned before, some methodologies and techniques are recommended for mitigating the non-desirable effects during titanium processing and analyzed in more detail, is its unique tool wear characteristics especially in light of manufacturing automotive components. Thus, this study is expected to primarily assist in the reduction of the processing cost of titanium and its alloys for automotive component manufacture. This will help reduce the operating cost of a road vehicle in terms of better fuel economy due to the reduced mass, which in turn translates to better energy efficiency. TITANIUM IN THE AUTOMOTIVE

A protocol has been developed that produced the type of lunar soil abrasion damage observed on Apollo spacesuits. This protocol was then applied to four materials (Kevlar (DuPont), Vectran (Kuraray Co., Ltd.), Orthofabric, and Tyvek (DuPont)) that are candidates for advanced spacesuits. Three of the four new candidate fabrics (all but Vectran) were effective at keeping the dust from penetrating to layers beneath. In the cases of Kevlar and Orthofabric this was accomplished by the addition of a silicone layer. In the case of Tyvek, the paper structure was dense enough to block dust transport. The least abrasive damage was suffered by the Tyvek. This was thought to be due in large part to its non-woven paper structure. The woven structures were all abraded where the top of the weave was struck by the abrasive. Of these, the Orthofabric suffered the least wear, with both Vectran and Kevlar suffering considerably more extensive filament breakage.

The paper presents the development of a real-time engine combustion monitoring system, based on direct measurement of engine acoustic emission, for on-board application. Acoustic emission contains information about several processes taking place within the engine. The combustion process could in fact be monitored by real-time processing acoustic data, and also other features related to engine operation are contained in the very same signal (such as valve closing events, and both engine and turbocharger speed). The paper describes the development of real-time signal processing algorithms that could be integrated in the actual ECU software, in order to improve combustion diagnosis and control by extracting in-cylinder pressure rise rate information from the overall engine noise. In particular, the ability to effectively reconstruct in-cylinder pressure rise rate under all engine operating conditions would allow for a closed-loop combustion control system. Since the combustion acoustic emission signal to noise ratio may become particularly low, the paper shows that combustion quality may still be roughly recovered, thus providing information that can be used to monitor and diagnose abnormal combustion modes, such as knocking and misfiring (or partial burns). Experimental tests have been carried out in a test-cell environment. Knocking and misfiring were externally induced, in order to evaluate the signal processing algorithms performance.

Specific power and efficiency of gasoline engines are influenced by factors such as compression ratio and Spark Advance (SA) regulation. These factors influence the combustion development over the crank angle: the trade-off between performance and the risk of irreversible damages is still a key element in the design of both high-performance (racing) and low-consumption engines. This paper presents a novel approach to the problem, with the objective of defining a damage-related and operating conditions-independent index. The methodology is based on the combined analysis of indicating parameters, such as Cumulated Heat Release (CHR), Indicated Mean Effective Pressure (IMEP) and 50% Mass Fraction Burned (MFB50), and typical knock detection parameters, estimated by means of the in-cylinder pressure sensor signal. Knocking combustions have several consequences; therefore, they can be detected in many ways. As it is well known, knock excites the combustion chamber resonant frequencies, rising high frequency components in the in-cylinder pressure signal. Additionally, knocking combustions cause a higher heat flux through the combustion chamber walls, increasing the heat losses and lowering the IMEP: this effect can be observed by evaluating IMEP or CHR that are based on the low-frequency content of the in-cylinder signal spectrum. A knock detection index can then be based on the crossed-observation of two phenomena, one set in the low-frequencies range and the other one on the high frequencies range of the in-cylinder pressure signal. Knock-related parameters have been analyzed with a statistical approach, in order to define a detection strategy based on one single threshold value, to be used for all the engines, independently of engine speed and load: IMEP and CHR have been related to a typical high-frequency knock index, based on the Maximum Amplitude of Pressure Oscillations (MAPO) evaluated over the combustion angular window. It can be observed that, as knock intensity increases, the relationships between these parameters change. This change can be seized by evaluating the correlation coefficient between the parameters distributions and observing its trend as a function of SA (Spark Advance). The correlation coefficient is intrinsically normalized; therefore, the index range is the same for every engine operating condition, and the paper shows that the threshold level, too, is constant. The same approach can be applied to determine SA corresponding to the best combustion phase, simply by evaluating the correlation coefficient for IMEP and MFB50 distributions. The methodology has been successfully applied to different engines running in different speed and load conditions.

Brake squeal is caused by dynamic instability, which is influenced by its dynamic unstable structure and small disturbance of friction force variation. Recently, FE Analysis of brake squeal is applied for brake design refinements, which is based on dynamic instability theory. As same as the refinement of brake structure is required for brake squeal reduction, the refinement of pad materials is also required for brake effectiveness and brake squeal reduction. It is well known that friction film, which is composed of polymers like phenol formaldehyde resin and so on, influences for friction coefficient. Therefore it is expected that the refinement of polymers in pad materials enable higher brake effectiveness and less brake squeal. In this paper, Molecular Dynamics is applied for the friction force variation of polymers in pad materials. The MD simulation results suggest the reduction method of friction force variation of polymers. The refinement of pad materials is shown here based on the MD simulation results, which is assured by experiments. This paper shows the possibility of friction materials design with higher performance and less brake squeal.

Creep-resistant HPDC alloys MRI153M and MRI230D are designated to replace HPDC aluminum alloys in the production of different automotive and non-automotive components. Due to the specific chemical compositions of the MRI alloys; they contain alkaline elements (Ca, Sr) with high affinity to Cl ions, fluxless technology must be used for recycling The present paper describes an technology which was developed for recycling MRI alloys. This technology combines simultaneous bubbling and stirring during batch processing. This operation is performed in order to improve metal cleanliness and reduce the process duration, thereby increasing its efficiency. The mechanical properties of recycled alloys were tested and compared with those of primary alloys. The influence of clean scrap dilution with primary material was also explored. The results obtained illustrate a moderate influence of scrap addition on mechanical properties. This effect should be considered for a wide range of die cast components production. The paper also presents guidelines for MRI alloys scrap handling and recycling.

Planar Laser-Induced Fluorescence has been widely accepted and applied to measurements of fuel concentration distributions in IC engines. The need for such measurements has increased with the introduction of Direct Injection (DI) gasoline engines, where it is critical to understand the influence of mixture inhomogeneity on ignition and subsequent combustion, and in particular the implications for cyclic variability. The apparent simplicity of PLIF has led to misunderstanding of the technique when applied to quantitative measurements of fuel distributions. This paper presents a series of engineering methods for optimizing, calibrating and referencing, which together demonstrate a quantitative measure of fuel concentration with an absolute accuracy of 10%. PLIF is widely used with single component fuels as carriers for the fluorescent tracers. This paper shows that this method inadequately describes a real fuel spray, and presents instead a method that uses a fully fractionated multi-component fuel for PLIF diagnostics. A series of measurements is presented of fuel distribution, early injection DI homogeneity and cyclic variation of injector plumes in a DI single cylinder optical research engine. Copyright © 2008 SAE International.

Methanol is a genuine candidate on the alternative fuel market for internal combustion engines, especially within the heavy-duty transportation sector. Partially premixed combustion (PPC) engine concept, known for its high efficiency and low emission rates, can be promoted further with methanol fuel due to its unique thermo-physical properties. The low stoichiometric air to fuel ratio allows to utilize late injection timings, which reduces the wall-wetting effects, and thus can lead to less unburned hydrocarbons. Moreover, combustion of methanol as an alcohol fuel, is free from soot emissions, which allows to extend the operation range of the engine. However, due to the high latent heat of vaporization, the ignition event requires a high inlet temperature to achieve ignition event. In this paper LES simulations together with experimental measurements on an heavy-duty optical engine are used to study methanol PPC engine. After a successful calibration of the pressure trace in terms of required intake temperature and combustion model, the optical natural luminosity data is used to validate prediction of ignition kernel and vapor penetration length. Moreover, it is shown that the inlet temperature requirement is reduced by 47 K degrees when applying multiple injection strategy. Changing the injection strategy also affects the average temperature of combustion and thus the emissions rates. Additionally, an ignition sequence analysis is performed to identify the mode of combustion and the heat release (HR) distribution depending on the local equivalence ratio, recognizing characteristics of PPC regime. Based on this analysis, a conceptual heat distribution model for PPC engine and other low temperature combustion (LTC) engine concepts is proposed. (Less)

The combustion process in a homogeneous charge compression ignition (HCCI) engine is mainly governed by ignition wave propagation. The in-cylinder pressure, heat release rate, and the emission characteristics are thus largely driven by the chemical kinetics of the fuel. As a result, CFD simulation of such combustion process is very sensitive to the employed reaction mechanism, which model the real chemical kinetics of the fuel. In order to perform engine simulation with a range of operating conditions and cylinder-piston geometry for the design and optimization purpose, it is essential to have a chemical kinetic mechanism that is both accurate and computational inexpensive. In this paper, we report on the evaluation of several chemical kinetic mechanisms for methanol combustion, including large mechanisms and skeletal/reduced mechanisms. These mechanisms are evaluated in terms of homogeneous ignition delay time, laminar flame speed, and multi-phase simulations of HCCI heavy-duty engine. The results are compared with experimental data and evaluated in terms of the accuracy and computational cost. It was found that scattering of ignition delay time predicted from different chemical kinetic mechanisms reported in the literature under homogeneous mixture ignition conditions give rise to a high sensitivity of the engine in-cylinder pressure prediction to the selected mechanism. (Less)

Low temperature combustion concepts used in compression ignition engines have shown to be able to produce simultaneous reduction of oxides of nitrogen and soot as well as generating higher gross indicated efficiencies compared to conventional diesel combustion. This is achieved by a combination of premixing, dilution and optimization of combustion phasing. Low temperature combustion can be complemented by moving away from fossil fuels in order to reduce the net output of CO 2 emissions. Alternative fuels are preferably liquid and of sufficient energy density. As such methanol is proposed as a viable option. This paper reports the results from a simulation based investigation on a heavy-duty multi-cylinder direct injection compression ignition engine with standard compression ratio. The engine was simulated using two different fuels: methanol and gasoline with an octane number of 70. The primary objective of the study was to find the optimal engine settings which maximized the brake efficiency for the engine. A secondary objective was to find the optimal injection strategy and combustion mode that would result if the brake efficiency was targeted. Comparing methanol with gasoline, the brake efficiency was on average 5.5% higher with methanol. This increase stemmed from a reduction of in-cylinder exhaust loss which was due to higher specific heats and favorable combustion phasing. Furthermore there was a significant difference in the optimal injection strategy comparing methanol and gasoline. Due to the higher octane number of methanol, all the fuel could be injected before the start of combustion. Consequently, an injection strategy typical for the low temperature combustion concept partially premixed combustion resulted. The injection strategy with gasoline, on the other hand, was similar to what is typically found in conventional diesel engines.

Mechanical friction is a significant power dissipater in the internal combustion engine. In the effort of designing more efficient and less pollutant engines, friction reduction is certainly on the agenda to be investigated. Such investigation cannot be possible without an accurate measurement of the same quantity. This publication regards a continued study on the mechanical friction determination in an internal combustion engine using the Pressurised Motoring Method. In this work, the friction mean effective pressure of a four-cylinder compression ignition engine was investigated with varying engine speed and manifold pressurisation, using a dedicated high precision sensor for the correct determination of the cylinder Top Dead Centre position. Two different measurement sessions were carried out; in the first, air was employed as pressurisation medium, testing 32 different setpoints; in the second, instead, with the aim to test the effect of the variation of thermochemical properties of fluids on the thermodynamic loss angle, Argon was used in place of air in 18 different setpoints. In the motored condition it is widely accepted that the brake torque is a measure of the losses of the engine and therefore has to be supplied by the driver, in our case the AC motor. The 2000 rpm region was explored with the aim to investigate the high motoring brake torque observed in a previous work from the same authors [1]. An investigation of the volumetric efficiency effect on motoring brake torque is also presented in the paper. Values of IMEP, BMEP, FMEP, peak in-cylinder pressure, loss angle and other parameters are given. The loss angle measured at each setpoint using the TDC sensor is compared with the loss angle evaluated by the use of two thermodynamic methods developed by Stas' [2] and Pipitone [3].

Maximum fuel injection pressures for GDI engines is expected to increase due to positive effects on emissions and engine-efficiency. Current GDI injectors have maximum operating pressures of 35 MPa, but higher injection pressures have yielded promising reductions in particle number (PN) and improved combustion stability. However, the mechanisms responsible for these effects are poorly understood, and there have been few studies on fuel sprays formed at high injection pressures. This paper summarizes experimental studies on the properties of sprays formed at high injection pressures. The results of these experiments can be used as inputs for CFD simulations and studies on combustion behavior, emissions formation, and combustion system design. The experiments were conducted using an injection rate meter and optical methods in a constant volume spray chamber. Injection rate measurements were performed to determine the injectors’ flow characteristics. Spray imaging was performed using a high-speed video camera. Several spray properties such as the liquid spray penetration, spray plume angle, and the spray breakup point were determined as functions of the fuel injection pressure and injected fuel mass by image post-processing. The impact of fuel pressure on spray droplet size was also investigated using two-component Phase Doppler Interferometry. Piezoelectric injectors for diesel engines were used with modified nozzles that produce sprays resembling those generated in gasoline engines. Experiments were performed with fuel injection pressures ranging from 20 to 150 MPa, and chamber pressures of 0.1 and 0.6 MPa. In addition, four different nozzles with three different nozzle configurations and either 6 or 10 holes were used to determine how hole geometry affects spray formation. The study’s key findings are that increasing the fuel injection pressure advances spray breakup and creates smaller droplets, improving mixture formation and accelerating evaporation. The nozzle type and the ambient pressure both significantly affect aspects of spray behavior such as spray tip development.

© 2019 SAE International. All Rights Reserved. Natural gas, biogas, and biomethane are attractive fuels for compressed natural gas (CNG) engines because of their beneficial physical and chemical characteristics. This paper examines three combustion modes - homogeneous stoichiometric, homogeneous lean burn, and stratified combustion - in an optical single cylinder engine with a gas direct injection system operating with an injection pressure of 18 bar. The combustion process in each mode was characterized by indicated parameters, recording combustion images, and analysing combustion chemiluminescence emission spectra. Pure methane, which is the main component of CNG (up to 98%) or biomethane (> 98 %), was used as the fuel. Chemiluminescence emission spectrum analysis showed that OH∗ and CN∗ peaks appeared at their characteristic wavelengths in all three combustion modes. The peak of OH∗ and broadband CO 2 ∗ intensities were strongly dependent on the air/fuel ratio conditions in the cylinder. Lower OH∗ and CO 2 ∗ intensities were observed with lean air/fuel mixtures because under these conditions, more air was present, the combustion reactions were slower, and the cylinder pressure was higher. CN∗ was formed by the spark plasma and was detected over a particularly long period when using a dual coil ignition system. The intensities of the OH∗ and CN∗ signals correlated when using this ignition system. Combustion image analysis showed that the flame had a wrinkled boundary in stoichiometric and lean burn modes and was especially distorted in stratified mode. No yellow soot luminescence was observed during homogeneous combustion. However, the emission spectra and combustion images acquired during stratified combustion showed that soot formation occurred due to the presence of fuel-rich areas with inadequate mixing in the cylinder. The difficulty of maintaining stable fuel injection, achieving proper air/fuel mixing, and ensuring stable flame propagation in lean air/fuel mixtures increased cycle-to-cycle variations. However, the homogeneous lean burn and stratified combustion modes achieved significantly lower indicated specific fuel consumption values than stoichiometric combustion.

The double compression expansion engine (DCEE) is a promising concept for high engine efficiency while fulfilling the most stringent European and US emission legislation. The complete thermodynamic cycle of the engine is split among several cylinders. Combustion of fuel occurs in the combustion cylinder and in the expansion cylinder the exhaust gases are over expanded to obtain high efficiency. A high-pressure tank is installed between these two cylinders for after-treatment purposes. One proposal is to utilize thermal reduction of nitrogen oxides (NOx) in the high-pressure tank as exhaust temperatures can be sufficiently high (above 700 °C) for the selective non-catalytic reduction (SNCR) reactions to occur. The exhaust gas residence time at these elevated exhaust temperatures is also long enough for the chemical reactions, as the volume of the high-pressure tank is substantially larger than the volume of the combustion cylinders. In this paper a single-cylinder D13 engine was run together with a 30 l high-pressure tank, with and without a diesel oxidation catalyst (DOC). AUS 32 and an ammonia-water solution (AAS 25) are injected before the high-pressure tank at different exhaust temperatures to study the thermal reduction of NOx produced from the combustion and the impact of the DOC. Additionally, the normalized stoichiometric ratio (NSR) was swept to evaluate the maximum NOx reduction potential of SNCR. Experimental results showed that very high NOx conversion efficiencies could be achieved for both AUS 32 and AAS 25. NOx conversion efficiencies of 80 % were obtained for NSR = 3. At stoichiometric NOx reductant dosing (NSR = 1), 40 % of nitrogen oxides could be reduced thermally. Presence of a DOC would decrease the efficiency of the thermal reduction as it oxidizes ammonia. At exhaust gas temperatures below 400°C, platinum in the DOC reduced NOx with a maximum conversion efficiency of 31 % at 350°C. (Less)

This paper presents the methodology for structural analysis of a high-speed Diesel engine aluminum cylinder head for Pick-up application, considering the finite element method. As boundary conditions, it was considered the loads from the bolts tightening process, combustion peak pressure, and thermal loading. The stresses generated during the assembly of the valve seats and valve guides were also evaluated. The valve train dynamic loads were not analyzed or considered in this paper, due to its negligible effects at the critical regions. The FE model contains the upper part of the crankcase and the entire cylinder head. Heat transfer coefficients at the water jackets were obtained from a CFD calculation and used at the heat transfer analysis to evaluate the thermal stresses.

This paper compares the performance, efficiency, emissions and combustion parameters of a prototype two cylinder 430 cm 3 engine which has been tested in a variety of normally aspirated (NA) modes with compression ratio (CR) variations. Experiments were completed using 98-RON pump gasoline with modes defined by alterations to the induction system, which included carburetion and port fuel injection (PFI). The results from this paper provide some insight into the CR effects for small NA spark ignition (SI) engines. This information provides future direction for the development of smaller engines as engine downsizing grows in popularity due to rising oil prices and recent carbon dioxide (CO2) emission regulations. Results are displayed in the engine speed, manifold absolute pressure (MAP) and CR domains, with engine speeds exceeding 10000 rev/min and CRs ranging from 9 to 13. Combustion analysis is also included, allowing mass fraction burn (MFB) comparison. Experimental results showed minimum brake specific fuel consumption (BSFC) or maximum brake thermal efficiency (ηTH) values in the order of 220 g/kWh or 37% could be achieved. A maximum brake mean effective pressure (BMEP) of 13 bar was also recorded at 8000 rev/min.

In this paper procedures for estimating the sound absorption coefficient when the specimen has inherently low absorption are discussed. Examples of this include the measurement of the absorption coefficient of pavements, closed cell foams and other barrier materials whose absorption coefficient is nevertheless required, and the measurement of sound absorption of muffler components such as perforates. The focus of the paper is on (1) obtaining an accurate phase correction and (2) proper correction for tube attenuation when using impedance tube methods. For the latter it is shown that the equations for tube attenuation correction in the standards underestimate the actual tube attenuation, leading to an overestimate of the measured absorption coefficient. This error could be critical, for example, when one is attempting to qualify a facility for the measurement of pass-by noise. In this paper we propose a remedy – to measure the actual tube attenuation and to use this value, as opposed to the value recommended by the standards, to correct the measured sound absorption. We also recommend an alternative way to determine the microphone phase error.