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Coal dust in continuous mining tunnels is extremely hazardous to drivers and other workers. In order to solve this problem, a continuous mining tunnel model is built based on computational fluid dynamics and gas–solid two-phase flow theory. Fluent 19.2 software is used to analyze the effects of air pipe outlet location (d) and external air curtain (EAC) outlet air velocity (vvent) on dust dispersion. The effects on the characteristics of dust dispersion are analyzed separately, and it is concluded that d=7 m is optimal. At this distance, the average dust concentration at the breathing zone height is low, and there is no significant fluctuation or rebound in the dust concentration during the dispersion process. When vvent=6 m/s , the highest dust separation efficiency of 89.3% occurs at a breathing height of y=1.6 m and x=5.82 m (133 mg/m3). The driver's position is protected with a dust separation efficiency of 79.2%. As the vvent value increases, the dust separation efficiency increases slowly. The cost of generating airflow should be considered for dust reduction efficiency, and an optimal vvent of 6 m/s is recommended. The findings of this study can provide a theoretical basis for the selection of ventilation parameters for air curtain dust reduction in continuous mining tunnels with rectangular cross section. [ABSTRACT FROM AUTHOR]

Sludge production increases year by year, which causes great environmental pressure. Low-temperature sludge drying technology is a kind of technology with energy conservation and environmental protection, which is widely favored by the sludge drying industry. The distribution of airflow in the drying chamber is the key factor affecting the drying performance of sludge drying system. In this paper, a uniform flow structure was designed, and a numerical simulation study of the designed flow field in the designed drying chamber was carried out by STAR-CCM+ software. The uniform flow structure of the sludge drying chamber and the optimal flow field distribution conditions on the drying chamber and conveyor belt were obtained so that the uniformity of air distribution in the sludge drying chamber and conveyor belt was improved, and the drying performance of the sludge low-temperature drying system was improved. The effectiveness of the numerical simulation was verified by experiments. The experimental results showed that when the number of shunt plates is three, the shape is an involute arc plate, the distance between the first and third shunt plate is 1,600 mm, and the distance between the second and first shunt plate is 700–900 mm. The flow field distribution on the drying room and the conveyor belt was the most uniform when the inlet wind speed was between 25 and 35 m/s. In addition, there is a strong correlation between the experimental results and the simulation results, which can prove the effectiveness and reliability of the numerical model. The airflow distribution inside the drying room was very uneven: the airflow would change direction with the shape of the obstacle, and the direction of airflow movement was easily affected by the shape of the shunt plates. Therefore, the shape of the shunt plates of the flow sharing structure was different, and the effect of the flow field was also different. Therefore, it was necessary to optimize the distribution uniformity of the flow field in the drying room. STAR-CCM+ software was used to optimize the flow field of the drying room, and the distribution of the velocity field was mainly considered. Through numerical simulation, the shape, quantity, and layout of the flow sharing structure were simulated and optimized, and the flow sharing structure that could improve the uniformity of air distribution in the drying room was designed. As long as these problems are solved, the low-temperature drying system could greatly improve the energy consumption of sludge dewatering, carry out sludge reduction treatment, and also be applied in large-scale industrialization, greatly reducing the problem of sludge treatment and reducing the environmental pollution. [ABSTRACT FROM AUTHOR]

The flow of air inside a vertical slender long duct with a temperature difference between the horizontal walls characterized by the Rayleigh number R a and a pressure gradient in the horizontal direction characterized by the Reynolds number R e is studied using the lattice Boltzmann method. In this case, the longitudinal rolls found in ducts with a width larger than the height cannot develop and the flow remains quasi-two-dimensional. Therefore, a two-dimensional approach is used, considering periodic boundary conditions on the vertical walls. For R a c < R a ≤ 2. 0 × 1 0 5 with R a c the critical Rayleigh number for thermal convection, there are two transitions at R e 0 (R a) and R e C P (R a) , R e 0 < R e C P . The first transition at R e 0 has a sharp decrease in the average Nusselt number and for 0 < R e < R e 0 the temperature difference between the horizontal walls is more important than the pressure gradient. The second transition at R e C P marks the appearance of a conductive Poiseuille flow with no thermal convection. For 1. 0 × 1 0 5 ¡ R a there is a third transition at R e M , R e 0 < R e M < R e C P . For R a < 1. 0 × 1 0 5 and R e 0 < R e < R e C P , and for 1. 0 × 1 0 5 < R a and R e M < R e < R e C P , the pressure gradient dominates over the pressure gradient. Both the temperature difference and the pressure gradient are important for 1. 0 × 1 0 5 < R a and R e 0 < R e < R e M with an appreciable decrease of the average Nusselt number at R e 0 and R e M . [ABSTRACT FROM AUTHOR]

Human airways represent a complex flow system with a spatially and temporally variable character of air flow during respiration. In this paper, we experimentally studied the oscillatory flow of air with monodispersed micron-sized liquid particles in a transparent, anatomically realistic model of human upper airways and several bronchi generations using phase-Doppler anemometry (PDA). The PDA provided point-wise high-frequency measurements of axial velocities of individual aerosol particles in multiple positions of the airways (in the trachea and the upper bronchi) for three breathing regimes with a sinusoidal course. Typical time-resolved velocity plots at several positions within the model were documented and analysed using dimensionless criteria. Local mean air velocity and turbulence time-lines disclosed specific flow dynamic features in the multiple bifurcation system, namely the transit of vortical structures, oscillations induced by flow reversals, and inspiratory flow separations behind bifurcations. The results elucidated the laminar, transitional and turbulent flows during inspiratory and expiratory breathing phases. The character of the flow varies significantly with position in the airways, while the breathing regime has a generally low effect on the flow character. Inspection of the flow in the terminal branches indicated the need to add further branches for more realistic results there. [ABSTRACT FROM AUTHOR]

Present wearable sensors are able to measure the frequency of vital signs such as respiration rate and heartbeat rate, but unable to measure those quantitatively, e.g. respiratory volume and heartbeat strength. Meanwhile, airflow at mouth contains both the respiration and the heartbeat quantitative signals. In this study, we propose a calibration method for a wearable vital sensor attached on the chest using the airflow at the mouth for quantitative respiration monitoring. An artificial ventilator and an experimental animal were introduced as test benches prior to human clinical experiment. As a proof of concept, a micro‐electro mechanical systems (MEMS) airflow sensor and a wearable accelerometer were implemented to both the test benches. The velocity output of the piston motion measured by the wearable sensor conformed with the airflow rate output, and the obtained results indicated that the wearable sensor can monitor not only the frequency of vital signs but also quantitative magnitudes such as the respiratory volume. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Respiratory diseases, including the cronic obstructive pulmonary disease (COPD) are among the leading causes of death worldwide. To date, there is no physical examination procedure that can quantify important parameters within a specific lesion area inside the lung. In this study, we propose a novel sensor probe system consisting of a basket forceps and 2 pressure sensors to simultaneously measure the expiratory airflow and the static pressure inside the pulmonary airway. A Pitot tube mechanism using 2 pressure sensors is introduced in the system for measuring both the physical quantities. Small fiber‐optic pressure sensors with 0.3 mm diameter were utilized, and both the airflow rate and the static pressure characteristics were evaluated for obtaining the calibration curves. Finally, the proposed sensor system was implemented to measure both the airflow and pressure in an artificial ventilator and an experimental animal. The measurement of expired airflow and static pressure inside the airway of a rat with the diameter of 1.8 mm were demonstrated. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

In addressing the substantial greenhouse gas emissions produced by the energy-intensive Haber–Bosch synthesis, this study investigates the viability of sustainable nitrogen fixation (NF) via low-temperature plasma systems energized by renewable sources. Utilizing vibrational coherent anti-Stokes Raman scattering as a diagnostic tool, we probed the nitrogen rovibrational temperature and population dynamics within a DC glow discharge in atmospheric air, a setting with considerable promise for eco-friendly fertilizer production. Besides, density for atomic N , O , and NO was quantified by laser-induced fluorescence (LIF) or two-photon absorbed LIF methods. Our findings reveal a quasi-equilibrium between rotational and vibrational energy states in the DC glow discharge environment, reaching an approximate value of 3500 K at the discharge core. The discharge parameters, discharge current, air flow rate, and discharge gap influence the rovibrational temperature, density distribution of species of interest, and the NF energy cost. However, the influences induced by these parameters are of limitations. Further analysis implies that the high gas temperature and its induced significant vibrational-rotational and vibrational-translational energy exchange are mainly responsible for the non-ideal NF energy cost. [ABSTRACT FROM AUTHOR]

The two-phase countercurrent flow limitation (CCFL) in horizontal channels is important in relation to nuclear reactor safety. In this study, we aim to investigate the CCFL characteristics and the flow behaviors in horizontal circular pipes with small diameters. The effects of pipe diameter and the water head in the upper plenum on CCFL characteristics are experimentally studied. An image-processing technique and statistical treatments are implemented to analyze the horizontal countercurrent flow. The results show that the CCFL characteristics for the horizontal circular pipes with small diameters can be well correlated using the dimensionless parameters, which are based on adding fluid viscosity to the Wallis parameters. The CCFL characteristics are significantly affected by the pipe diameter and are slightly affected by the water head above the horizontal pipe. The gas–liquid interface fluctuates with certain periods, and flow pattern transitions happen in the horizontal air–water countercurrent flow. As the air flow rate increases, the occurrence location of the liquid slug appears to shift towards the water entrance. In addition, the further away from the water entrance, the lower the average of liquid holdup. [ABSTRACT FROM AUTHOR]

Fruit tree frost, an agricultural meteorological disaster primarily occurring in spring, severely impacts the growth and development of trees and fruit set. Therefore, exploring the temperature change rules of fruit trees during frost events is of considerable importance. This study used a T40 unmanned aerial vehicle (UAV) as the test vehicle based on the air disturbance frost prevention principle. The airflow field change pattern of the UAV was explored using the computational fluid dynamics simulation method, and the reliability of the multi-rotor UAV in frost prevention was verified using field tests. Setting the UAV height at 6.0 m above the ground and the rotor speed at 1000 r min−1, it was found that under the conditions of the inverse temperature phenomenon, the temperatures of different altitude layers will eventually converge to a stable value when the UAV down-rotating airflow is disturbed, which could be completed rapidly within 20 s. The results of the field test also showed that when the fruit trees reached the critical temperature of frost at the flowering stage, UAV intervention could have a substantial effect on the warming of the near-surface layers, whose warming amplitude was in the range of 2.5 °C–3 °C. This study provides a reliable method for mitigating frost, which serves as an important theoretical and guiding basis for improving agricultural frost disasters in China. • A multi-rotor UAV is used to test frost protection performance on fruit trees. • The temperature field characterizations are obtained. • The anti-frost effectiveness of UAV intervention is confirmed. [ABSTRACT FROM AUTHOR]

Nonequilibrium flows of air components behind reflected shock waves are systematically studied on the basis of several theoretical models for the rate coefficients of fully coupled vibrational energy exchanges and chemical reactions. Numerical simulations are performed in the frame of the state-to-state approach under initial conditions corresponding to recent shock-tube experiments in mixtures O 2 /Ar, NO/Ar, NO/N 2 /Ar. The model takes into account partial vibrational relaxation between the incident and reflected shock waves, state-resolved dissociation, recombination, exchange reactions with formation of NO in the vibrationally excited states, as well as vibrational–vibrational and vibrational–translational energy transitions. It is shown that for oxygen, relaxation between the incident and reflected shocks is not frozen, and taking it into account in the most test cases considerably improves the agreement of calculated and experimentally measured pressure. For NO-containing mixtures, the effect of intermediate relaxation is weaker. Average deviation of the number density of molecular species with respect to the experimental one is analyzed for several hundreds of numerical simulations; on the basis of these estimates, recommendations are given for the best choice of model parameters. These recommendations can be used for modeling high-temperature flows, in particular, under reentry conditions. • Recent shock-tube experiments in air species are simulated numerically. • State-to-state models of vibrational–chemical coupling are validated. • Good agreement with experimental data is shown. • Recommendations are given for the best choice of model parameters. [ABSTRACT FROM AUTHOR]

Background The aim of this study is to investigate the different approaches to thermal challenges, both cold and warm, used in dynamic infrared thermography for reconstructive surgery, and explore whether it affects the success of preoperative perforator mapping. Methods Literature was collected from Ovid Medline, Embase, PubMed, and Cochrane. The references of the full-text articles located from the original search were also appraised. Thirteen articles were extracted for the final qualitative analysis. A systematic review was then conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Results Thirteen articles looked at a cold challenge, which included airflow cooling, direct contact cooling, and evaporation-based cooling. Two articles investigated warm challenges. One paper used no challenge, suggesting it unnecessary with a highly sensitive camera. All cold challenges were positively supported by a high level of flap perfusion success and/or a high level of correlation with other forms of investigation. Conclusion Cold challenges were overall superior to no challenge and warm challenges; however, this conclusion is limited by the small participant size, the possibility of detection bias, and poor methodology detailing. Airflow cooling—specifically, using a desktop fan to blow air for 2 minutes—was noted to likely cause the least discomfort due to a low cooling capacity yet simultaneously maintain effectiveness and allow for a uniform cooling application. Warm challenges showed less conclusive results and were restricted by lack of studies. This topic would benefit from larger scale studies that compare multiple approaches while using standardized equipment to eliminate confounding factors. [ABSTRACT FROM AUTHOR]

It is important to have an awareness of the factors that may impact DNA transfer. Here we perform a preliminary study on the impact of airflow on the transfer of DNA from biological materials. Common airflows at different distances from their source were determined. Biological materials on different substrates were exposed to relatively high airflows. Tests showed that airflow can transfer detectable levels of DNA away from where they were deposited, especially blood, less so saliva and touch DNA. Information on indirect transfer of biological materials due to airflow can assist activity level evaluations and considerations towards improvements in laboratory design and procedures. [ABSTRACT FROM AUTHOR]

It is important to have an awareness of the factors that may impact DNA transfer. Here we perform a preliminary study on the impact of airflow on the transfer of DNA from biological materials. Common airflows at different distances from their source were determined. Biological materials on different substrates were exposed to relatively high airflows. Tests showed that airflow can transfer detectable levels of DNA away from where they were deposited, especially blood, less so saliva and touch DNA. Information on indirect transfer of biological materials due to airflow can assist activity level evaluations and considerations towards improvements in laboratory design and procedures. [ABSTRACT FROM AUTHOR]

Understanding the characteristics of coal spontaneous combustion (CSC) in goaf under different porosities is crucial for comprehending the mechanism of CSC and its prevention and control. In this paper, a multi-field coupled model of CSC in the goaf, considering porosity variation, is developed to investigate the effect of porosity on the CSC characteristics in the goaf. The results indicate that, as the goaf depth increases, both porosity and permeability decrease. When the highest goaf porosity is 25%, the average airflow velocity is between 0.00134 and 0.00139 m/s. In contrast, the average airflow velocity in the goaf with a porosity of 40% is approximately six times greater than that of the goaf with a porosity of 25%. As the goaf porosity increases, the overall oxygen concentration, temperature, and oxidized zone area also rise. Moreover, the oxidation zone area can be quantified and visualized, thereby enabling more effective prediction of the CSC risk in the goaf. The findings of the study have a positive significance in guiding the prevention and control of coal fires. [ABSTRACT FROM AUTHOR]

The effect of the mainline slope on the ceiling temperature profile in a branched tunnel has not been clarified nor included in existing models. Thus, in this paper, the numerical code was employed to investigate the induced airflow velocity and gas temperature beneath the ceiling in a branch tunnel with a sloped upstream mainline. The mainline slope varied from 1% to 7%, with an interval of 1%. Five fire power of 3 MW, 5 MW, 10 MW, 15 MW, and 20 MW are employed on each slope. The airflow velocity and the longitudinal temperature in the mainline tunnel are measured and analyzed. Results show that the stack effect obviously occurred, which caused longitudinal velocity to prevent the smoke reverse flow in the mainline. The induced airflow velocity in the upstream inclined mainline is higher with increasing slope, and the dimensionless velocity is normalized well by the proposed expression. The maximum ceiling temperature is independent of the mainline slope and correlated well by Q*2/3, but the effect of the mainline slope on temperature longitudinal decay is worth considering. Finally, a normalized expression for longitudinal temperature decay in an inclined mainline is proposed by taking the fire power and mainline slope into account. [ABSTRACT FROM AUTHOR]

The Richards equation is commonly used to model the flow of water and air through soil, and it serves as a gateway equation for multiphase flows through porous media. It is a nonlinear advection–reaction–diffusion equation that exhibits both parabolic–hyperbolic and parabolic–elliptic kind of degeneracies. In this study, we provide reliable, fully computable, and locally space–time efficient a posteriori error bounds for numerical approximations of the fully degenerate Richards equation. For showing global reliability, a nonlocal-in-time error estimate is derived individually for the time-integrated H^1(H^{-1}), L^2(L^2), and the L^2(H^1) errors. A maximum principle and a degeneracy estimator are employed for the last one. Global and local space–time efficiency error bounds are then obtained in a standard H^1(H^{-1})\cap L^2(H^1) norm. The reliability and efficiency norms employed coincide when there is no nonlinearity. Moreover, error contributors such as space discretization, time discretization, quadrature, linearization, and data oscillation are identified and separated. The estimates are also valid in a setting where iterative linearization with inexact solvers is considered. Numerical tests are conducted for nondegenerate and degenerate cases having exact solutions, as well as for a realistic case and a benchmark case. It is shown that the estimators correctly identify the errors up to a factor of the order of unity. [ABSTRACT FROM AUTHOR]

There are many factors that may affect the longevity of or guide the use of canine training aids. Literature to date has mainly focused on identifying the headspace volatiles associated with training aids or odors and only minimal research exists into how different variables may alter those volatiles. The current study examines several factors affecting canine training aids: humidity, air flow, transportation, and operational deployment, using the triacetone triperoxide polymer odor capture-and-release canine training aid (TATP POCR) as the target. The TATP POCR is an absorption-based canine training aid developed to be used to safely train canines to detect the odor of the explosive TATP in operational settings. Comparisons of the TATP POCR to neat TATP are made throughout the manuscript. First, humidity increased the background components of the POCR matrix, as well as the amount of TATP recovered was above the POCR. Humidity thus affected the amount of TATP detected but did not prevent detection. Second, air flow lessened the lifetime of the TATP POCR. Third, the practice of using primary and secondary containment successfully prevented contamination, cross-contamination, and significant target loss, thereby maintaining kit integrity. Finally, the absorption of background odors from training environments was not observed. TATP headspace concentrations between a Deployed and Control POCR kit were not significantly different at time 0 (i.e., upon opening), which suggests that the operational use does not affect the function of the TATP POCR system. This information provides pivotal evidence for explosives detection canine handlers or trainers who utilize the TATP POCR. [ABSTRACT FROM AUTHOR]

We used large-eddy simulation (LES) to numerically simulate two differently driven indoor airflows occurring in a multizone environment. In the first case, air flowed from one zone to another through a small hole driven by the total pressure difference. In the second case, unbalanced airflows arose from the buoyancy effect, which was generated by a heat source present in a specific location. To validate the LES prediction for the indoor flow analysis, we compared our simulation results with the chamber facility experimental results and other simulation results. Based on this validation, we confirmed that the LES reliably simulates indoor airflow. In addition, we discussed the flow characteristics and investigated the feasibility of modeling the flow rate through openings using an orifice formula. [ABSTRACT FROM AUTHOR]

Purpose: Upper respiratory tract complaints are common in the general population. A safe, non-pharmacologic treatment would be an attractive option for many patients either as an alternative to existing therapies, or as a complementary therapy. This study assessed the acceptability, safety and possible efficacy of a nasal airflow oscillation device in a group of people suffering chronic nasal congestion. Methods: Subjects with a known history of nasal congestion, but without fixed anatomical obstruction, participated in a prospective clinical study. Efficacy was assessed using peak nasal inspiratory flow (NPIF) and a 10-point visual analogue scale (VAS) administered before and after the oscillation device had been worn for twenty minutes. Results: Twenty-one subjects (mean age 37 years; 43% female) were enrolled in the study. After treatment with the small nasal airflow oscillation device for twenty minutes, average NPIF increased significantly from 84.8 L/minute to 99.0 L/minute (p < 0.05). There was a corresponding significant reduction in the VAS score for nasal congestion (p < 0.05). Similar significant improvements were also seen for the immediate sensation of nasal drainage, sinonasal pressure and overall sinonasal symptoms (p < 0.05). There was no change in the sense of smell (p = 0.37). Subjects rated ease of use highly; average = 9.1 (Range 7–10). Conclusion: Treatment of nasal congestion with the nasal airflow oscillation device was found to result in significant improvement in NPIF after twenty minutes of use. Initial patient-reported outcomes improved significantly, and the treatment was safe and highly acceptable. Trial registration: Public clinical trial registration: Universal Trial Number (U1111-1259-0704). Australian New Zealand clinical trials registration: ACTRN12623001307695. [ABSTRACT FROM AUTHOR]

Drying is a widely recognized process that reduces the need for storage and shipping weight, keeps free water out of the product, and prolongs its shelf life. An infrared dryer was designed to dry apples under different drying conditions. Apple slices of 6‐, 4‐, and 2‐mm thicknesses were dried at intensities 0.130, 0.225, and 0.341 W/cm2 and airflow 1.0, 0.5, and 1.5 m/s. The dehydrating period was prolonged with higher airflow and shortened with higher infrared intensity (IR). The shortest dehydrating period was verified by 190 min at 0.341 W/cm2, 0.5 m/s under 2 mm thickness. Increasing the sample thickness from 2 to 4 mm and then to 6 mm resulted in an 84% and 192% increase in drying time, respectively. Dehydrated apples had water activity values ranging from 0.30 to 0.40. The shrinkage ratio increased with an increase in infrared radiation intensity. However, it decreased with an increase in air velocity, while the rehydration ratio decreased with an increase in radiation intensity and increased with an increase in air velocity. Regarding total color change, apple slice thickness was a major factor. The effective diffusivities varied between 2.6 and 9.0 헑10−10 m2/s under different drying conditions. The dehydrating curves of apples were best described by the model developed by Midilli et al. [ABSTRACT FROM AUTHOR]

Bubble screens are used at sea locks to mitigate salt intrusion into inland water systems. In this paper the effectiveness of a bubble screen in delaying the mixing of salt and freshwater via lock exchange was studied. Laboratory-scale experiments investigating the flow field and mixing caused by a bubble screen are presented. The tests include both the homogeneous situation of freshwater on both sides of the screen and the inhomogeneous situation where there is an initial density difference across the screen, which leads to a density current after the lock gate is removed or opened. Optical measurement techniques were applied, giving spatially detailed flow velocities and densities. The parameters varied between tests are the airflow discharge and the bubble size. The results show that the bubble size in the screen had a significant effect with a screen with bubbles of 1–2 mm being more effective at generating a surface flow in the homogeneous case but less effective at keeping the fresh and salt sides separated in the inhomogeneous case, when compared with a screen of 4–6 mm bubbles. The point of maximum effectiveness for separating salt and fresh sides was also shown to be dependent on bubble size. [ABSTRACT FROM AUTHOR]

Previous studies showed that opening windows could help with kitchen ventilation in pollutant removal. However, no studies have systematically examined the impacts of window positions on kitchen hood performance, and there is insufficient information on indoor airflow characteristics and pollutant distribution from makeup air through open windows. Therefore, the objective of this study was to use a validated computational fluid dynamics approach with CO2 as an indoor air quality indicator (a surrogate for cooking emissions) to understand the impacts of exhaust flow rate and the window opening position on the flow characteristics, concentration distribution, and capture efficiency (CE) of the hood. We conducted four-point validation tests of the numerical models based on CO2 concentration and temperature measurements under steady-state conditions. The validated models were subsequently used in simulations to understand the effects of six different window opening positions and the two exhaust flow rates on exposure. We found that the CO2 concentration could be better reduced by having windows open at the higher location. Generally, the front windows were more effective with CE > 80 % , followed by the back and the side windows, respectively. We also found that as the exhaust flow rate increased from 6.72 to 12.16 m3/min, CE reached >75% for all window positions, where the most significant increase was 1.58 times for the lower side window. To sum up, changing the relative position of the window and the exhaust hood could help disperse the incoming airflow from the window, improve the kitchen's overall ventilation, and reduce pollutant concentration. [ABSTRACT FROM AUTHOR]

In this study, the fluorescence properties of Lumisis, a phosphor that can be easily applied to ultrafine wires, were evaluated. By evaluating the wavelength characteristics of Lumisis phosphor, we investigated the possibility of applying it to a dual-wavelength laser-induced fluorescence (LIF) measurement system and evaluated the accuracy of temperature measurements. The difference between the decrease in the percentage intensities of the red and green fluorescence of Lumisis phosphors showed that two-color LIF was possible. The Lumisis phosphor–mixture ratio was optimized as 1:1.25, and the average measurement error of the fluorescent wire was 0.20 K, as evaluated through uncertainty analysis. Finally, the application of this measurement method to hot air jet phenomena showed that this method accurately captures the temperature changes in hot air, thus proving its validity. [ABSTRACT FROM AUTHOR]

The energy harnessing from flow-induced vibrations (FIV) by an oscillating foil placed tandemly behind a circular cylinder (which serves as a vortex generator) is investigated. The foil is submerged in the wake produced by the fixed cylinder and could oscillate in the direction perpendicular to the incoming flow with single-degree freedom. The spacing ratio ranges from 1.0 to 5.0. The oncoming fluid velocity is U = 1–10 m/s, corresponding to the reduced velocity Ur = 3.81–38.08 and the Reynolds number Re = 9.58 × 103–9.58 × 104. Four harnessing damping ratios (ζharness = 0.0054–0.0216) are used to simulate the energy conversion conditions. The main conclusions are: (1) The optimal oscillation pattern related to the highest harnessed energy emerges as the spacing ratio close to 1.0. (2) The airflow energy converted by the foil is positively correlated with the harnessing damping ratio because the amplitude responses are similar at various harnessing damping ratios. A high velocity yields the highest harnessed power. (3) The harnessing efficiency of the foil could reach 48.89%, which is much more than that of an isolated flapping foil. [ABSTRACT FROM AUTHOR]

TiO2 was loaded on the porous nickel foam from the suspended ethanol solution and used for the photocatalytic removal of NOx. Such prepared material was heat-treated at various temperatures (400–600 °C) to increase the adhesion of TiO2 with the support. Obtained TiO2/nickel foam samples were characterized by XRD, UV–Vis/DR, FTIR, XPS, AFM, SEM, and nitrogen adsorption at 77 K. Photocatalytic tests of NO abatement were performed in the rectangular shape quartz reactor, irradiated from the top by UV LED light with an intensity of 10 W/m2. For these studies, a laminar flow of NO in the air (1 ppm) was applied under a relative humidity of 50% and a temperature of 28 °C. Concentrations of both NO and NO2 were monitored by a chemiluminescence NO analyzer. The adsorption of nitrogen species on the TiO2 surface was determined by FTIR spectroscopy. Performed studies revealed that increased temperature of heat treatment improves adhesion of TiO2 to the nickel foam substrate, decreases surface porosity, and causes removal of hydroxyl and alcohol groups from the titania surface. The less hydroxylated surface of TiO2 is more vulnerable to the adsorption of NO2 species, whereas the presence of OH groups on TiO2 enhances the adsorption of nitrate ions. Adsorbed nitrate species upon UV irradiation and moisture undergo photolysis to NO2. As a consequence, NO2 is released into the atmosphere, and the efficiency of NOx removal is decreasing. Photocatalytic conversion of NO to NO2 was higher for the sample heated at 400 °C than for that at 600 °C, although coverage of nickel foam by TiO2 was lower for the former one. It is stated that the presence of titania defects (Ti3+) at low temperatures of its heating enhances the adsorption of hydroxyl groups and the formation of hydroxyl radicals, which take part in NO oxidation. Contrary to that, the presence of titania defects in TiO2 through the formation of ilmenite structure (NiTiO3) in TiO2/nickel foam heated at 600 °C inhibits its photocatalytic activity. No less, the sample obtained at 600 °C indicated the highest abatement of NOx due to the high and stable adsorption of NO2 species on its surface. [ABSTRACT FROM AUTHOR]

This present investigation unveils a novel insight into the dominant airmass flows originating from both continental and maritime sources, shaping the characteristics of the raindrop size distribution (DSD), atmospheric instabilities, and cloud effective radius over Delhi (28.62°N, 77.17°E), the capital city of India. The investigation employs the Hybrid Single-Particle Lagrangian Integrated Trajectory model to analyze airmass back trajectories corresponding to days featuring rain events within the study area. An observable pattern emerges: days with rainfall driven by continental (maritime) activities experience higher (lower) atmospheric instabilities, which is validated by radiosonde measurements. This enhanced atmospheric instability leads to the prevalence of larger raindrops during continental-influenced rain events, in contrast to days marked by maritime airflow, as estimated from surface-based disdrometer measurements. Furthermore, observations from the INSAT 3D/3DR satellite indicate a tendency towards a smaller cloud effective radius associated with continental airmass inflow, as opposed to maritime inflow. Notably, a category of rain events characterized by ambiguous airmass back trajectories, referred to as mixed types, is identified. These mixed events showcase intermediary variations in the investigated atmospheric parameters, positioning them between the continental and maritime scenarios. The discernible differences in DSD characteristics between rain events influenced by continental and maritime activities yield fluctuations in the radar reflectivity-rain rate (Z-R) power law relations, which bear significance for the application of rain radar remote sensing. Hence, this investigation underscores the critical implication of incorporating airmass source information while characterizing rain features and related atmospheric parameters over a capital metropolis like Delhi. [ABSTRACT FROM AUTHOR]

This study focuses on the development of an advanced high heating rate thermobonding process for the manufacture of preforms and the metrological characterisation of the process. The process involves passing hot air, driven by pressure differential, through a textile stack consisting of several plies of a quadraxial fabric coated with a binder. Heat is transferred into the stack and into the binder by forced convection, melting the binder. The process is used in the same way to cool the stack and binder so that the plies are bonded together. The pressure differential compacts the stack. The comprehensive methodological characterisation of the process includes first determining the air permeability of the stack and thus the volume flow of air as a function of the number of plies stacked. Further characterisation focuses on a comprehensive determination of the heating behaviour in the individual plies as a function of time, using thermocouples and thermal imaging to determine the temperatures of hot air and textiles. These are compared and related using a mathematical approach as different values have been found. The results indicate high heating rates, reducing process time by at least 85% compared to previous binder activation methods. In addition, the cantilever method assesses the flexural stiffness of the processed stacks and shows a twofold improvement in bond strength compared to uncompacted stacks. Results and discussions include orifice based volume flow determination, thermography calibration, mathematical modelling, stiffness of bonded textile plies, process comparison, process control and potential energy savings. [ABSTRACT FROM AUTHOR]

Micropower generation and micropropulsion are two emerging fields where micro- and miniature-scale combustors are anticipated to play a significant role. Today, there is a growing interest in combustion-based direct energy conversion modules such as thermoelectric and thermophotovoltaic micropower generators. In this study, the effects of swirl addition to fuel flow and airflow on combustor operational envelope, flame blowout limit, combustion efficiency, exhaust gas temperature, mean outer wall temperature, emitter efficiency, and normalized temperature standard deviation of a miniature-scale (mesoscale) combustor are studied under various equivalence ratios. The findings demonstrate that swirling flows improve the flame blowout limit and operational envelope of the combustor; however, this improvement is more significant for airflow swirl. Besides simultaneous swirling flows of fuel and air result in the highest blowout limit. Additionally, it has been shown that swirl addition improves combustion efficiency and causes a significant amount of heat to be generated, which raises the temperature of the exhaust gas, the mean outer wall temperature, and the emitter efficiency. Furthermore, mean outer wall temperature and emitter efficiency have the highest values for simultaneous swirling flows of fuel and air. It is also observed that increasing the fuel flow swirl number generally lessens the normalized temperature standard deviation (NTSD) and consequently improves the combustor wall temperature uniformity, while for the airflow swirl case, a swirler with 30° vane angle for airstream has a lower NTSD than a 45° vane angle swirler. The results obtained in this study provide useful information for designing a combustion-based direct energy conversion module. [ABSTRACT FROM AUTHOR]

Drying harvested grain crops prior to storage is a crucial task in the prevailing climatic conditions of Europe. Drying is an extremely energy-intensive process. Its inappropriate application leads to environmental pollution, quality deterioration, and ultimately significant financial losses. Various methods are available for conducting drying operations, with the mixed flow dryer being one of the most employed approach. The mixed flow dryer utilizes air blower systems to redirect the flow of the granulate. Previous research has indicated that uneven distribution of grain flow around the air blower lamellae can cause drying irregularities. By leveraging insights from a long-established classical mechanical problem (the Brachistochrone problem) and harnessing the explicit dynamical modelling capabilities offered by contemporary computing technology (Discrete element method), we have successfully devised an optimized lamella geometry that minimizes the non-uniformity of particle flow. [ABSTRACT FROM AUTHOR]

Conventional multi-cylinder drying of paper and board involves a mixture of conductive drying from steam-heated dryer cylinders and convective drying by the flow of heated air over the surface of the paper web in the pockets. Pocket ventilation is a critical component in assisting heat and mass transfer during the drying process but is the primary contributor toward removing evaporated water from the web. Air temperature, velocity, and humidity are critical parameters involved in the convective drying process. This paper covers an experimental study involving the design and development of a small lab-scale setup for convective drying of various grades of paper and board, monitoring multiple parameters like paper temperature, moisture content, air humidity, temperature, and velocity measured in situ as the drying proceeds with continuous and accurate sampling capabilities for all parameters in the sample and the system. Instantaneous drying rates, heat, and mass transfer coefficients were also deduced for every time step till the paper completely dried. Furthermore, the coefficients obtained were also reported in the form of dimensionless correlations, and the results were compared against traditional correlations used in the modeling of paper drying. This data will be useful in process development, modeling, design, and the paper drying process simulation. [ABSTRACT FROM AUTHOR]

Nowadays, indoor air quality (IAQ) and the energy performance of buildings are two main scientific and technical challenges because they are in direct connection with human health and the depletion of energy resources. In this study, we analyzed the influence of an outdoor air flow introduced through a mechanical ventilation system, focusing on the two aforementioned topics. A standardized ventilation rate (25 m3/h/person) led to an increase in the indoor O3 concentration (from 5 μg/m3 to 50 μg/m3) and, simultaneously, to a decrease in the indoor CO2 concentration (from 2000 mg/m3 to 800 mg/m3), a decrease in the PM2.5 concentration (from 300 μg/m3 to 150 μg/m3), and the maintenance of a constant indoor HCHO concentration. In our study, a new, single indoor air quality index, IIAQ, is proposed. This new index presents different implications: on the one hand, it has the ability to simultaneously take into account several pollutant species, and on the other hand, it can prioritize the ventilation strategy that responds to the extreme values of a certain pollutant. Moreover, indoor air quality classes were elaborated, similar to energy classes. The possibility of using this new index simultaneously with energy consumption may lead to ventilation strategies that are adaptative to dynamic outdoor pollutant concentrations. [ABSTRACT FROM AUTHOR]

Future automotive mobility is predominantly electric. Compared to existing systems, the requirements of subsystems change. Air flow for cooling components is needed predominantly when the car is in rest (i.e., charging) or at slow speeds. So far, actively driven fans consuming power and generating noise are used in this case. Here we propose a passive adaptive system allowing for convection-driven cooling. The developed system is a highly adaptive flat valve derived from the bordered pit. It was developed through an iterative design process including simulations, both structural and thermodynamic. In hardwoods and conifers, bordered pits enable the challenging transport of vertical fluids by locally limiting damage. Depending on the structure, these can close at sudden pressure changes and take the function of valves. The result of the biomimetic abstraction process is a system-integrative, low-profile valve that is cheap to produce, long-lasting, lightweight, maintenance-free, and noise-free. It allows for the passive switching of air flow generation at the heat exchanger of the cooling between natural convection or an active airstream without the need for complex sensing and control systems. The geometric and material design factors allow for the simple tuning of the valve to the desired switching conditions during the design process. [ABSTRACT FROM AUTHOR]

The integrated design of multibypass augmented/ramjet combustors can reduce the weight of turbine-based combined cycle (TBCC) engines and improve the thrust-to-weight ratio, but low-resistance mixing and efficient stable combustion of multiple airflows over short distances are necessary prerequisites. In this study, a novel structure for a TBCC multibypass integrated augmented/ramjet combustor is proposed. The influence of the inlet aerodynamic parameters on the flow field, mixing efficiency, flow loss, and combustion performance of the combustor under different working modes was obtained via experimental and numerical methods. The experimental results show that the outlet mixing efficiency is greater than 86% in the double-bypass mode (DB-mode). While the triple-bypass mode (TB-mode) has a larger decrease, the total pressure loss is slightly reduced (by approximately 0.5%). The opening of the ram duct has a significant impact on the flow field, resulting in different rules for the influence of the inlet temperature on the outlet mixing efficiency: in the DB-mode, the mixing efficiency decreases with increasing inlet temperature, while the rule is completely opposite after entering the TB-mode. Because the dominant role of the two mixing zones in the flow field changes with the velocity, the inlet velocity has a significant impact on the mixing efficiency in the flow direction. The combustion simulation results show that the combustion efficiency in the DB-mode is almost always above 90% and the high-temperature zone is mainly concentrated downstream of the integrated strut. The radial temperature gradient increases and the combustion efficiency decreases in the TB-mode. [ABSTRACT FROM AUTHOR]

Mixing performance in the combustion chamber is important in achieving the efficiency of scramjet for its compact structure and the short residence time caused by high velocity. This study focuses on predicting the mixing performance in a viscous supersonic flow past the cavity flame holder in the scramjet, using the discontinuous spectral element method with direct numerical simulation. The arrangement and distribution of a series of cavities are calculated at various inlet velocities. By comparing the contours of Mach number and static temperature, as well as analyzing the airflow residence time with a new calculating formula and the drag based on the numerical results, it is concluded that higher inlet velocities result in faster stabilization. It also leads to longer airflow residence time when the supersonic flow passes through the dual-cavity with a tandem connection rather than the parallel one or the single-cavity structures. As for the shortened rear wall of cavities, these structures can decrease the drag quickly, but they also decrease the airflow residence time seriously, which destroys the mixing performance. In addition, these conclusions are applied to a practical case of the cavity flame holder, verifying the effectiveness of tandem dual-cavity structures in enhancing the mixing performance by increasing the airflow residence time and maintaining or reducing the drag. This study can provide valuable suggestions in further design of cavity flame holders for different flow conditions. [ABSTRACT FROM AUTHOR]

Suppression of vortex–airfoil interaction noise from a rod-airfoil model by virtual serrations and surface morphing formed by the leading-edge (LE) blowing was investigated experimentally in an anechoic wind tunnel. The control efficiency of the virtual serrations and surface morphing was evaluated and analyzed by setting different air flow rates (Q), deflection angles (α), and orifice number (M). Noise measurements by far-field microphones show that both can effectively reduce the peak tonal noise generated by the vortex–airfoil interaction, with the control efficiency increasing with the increment of flow rate Q. As for the LE serration, the noise reduction increases with the virtual serration amplitude ratio Av (=Ub/U∞, Ub: blowing velocity; U∞: wind speed), but decreases slightly with the deflection angle α. A reduction of 12–14 dB is obtained when Av = 3.7 and α = 0° or 10°, and there exists a critical amplitude of Av = 1.5, under which no noise reduction is achieved. Compared to the serration at the same flow condition, the virtual surface morphing has much lower control efficiency, with a maximum noise reduction of 3–5 dB. The flow visualization by the particle image velocimetry technique reveals that both build buffer zones in the front of the airfoil LE, preventing the vortices from directly impinging upon the solid LE, thus reducing the intensity of vortex–airfoil interaction. In particular, the virtual serration breaks up the large-scale vortex structure into small-scale vortices, manifesting its high noise control efficiency. [ABSTRACT FROM AUTHOR]

A rectangular cylinder, with an aspect ratio of 5, is a widely used bluff body in engineering practice. It undergoes intricate dynamical behavior in response to minute alterations in the flow angle of attack (α). These modifications invariably precipitate the failure of wake control for classical flow control methods with various α values. In this study, global linear instability, adjoint method, and sensitivity analysis are employed to identify the optimal position for flow control. It is found that the sensitive region gradually transitions from the leeward side to the downwind side of the model as α and Reynolds number (Re) increase. So, we set up airflow orifices for flow control in both positions. Jet flow control on the leeward side effectively inhibits vortex shedding (α ≤ 2°). High-order dynamic mode decomposition is employed to reveal the inherent mechanism of control. Suction control on the downside effectively mitigates the shear layer separation phenomenon induced by the altered spatial structure associated with higher α. A novel zero-net-mass-flux wake control, bionics-based breathe-valve control (BVC), is proposed to optimize the control effect. BVC is applicable for various α and Re, with optimal effectiveness achievable through jet velocity adjustments. The prediction-control approach in this investigation provides a targeted method to mitigate flow-induced vibration. [ABSTRACT FROM AUTHOR]

The air-lift reverse circulation drilling method enables efficient and continuous core extraction. However, the flow characteristics of gas–liquid–solid mixtures during core mass transport are complex, and developing a model to predict performance remains challenging. The flow characteristics of gas–liquid–solid mixtures inside the drill pipe are numerically analyzed by calculating the mixing transport of the core during the airlift process. By solving the momentum equations for multiphase flow, the distribution of physical quantities of three phases and pressure along the depth was calculated, and the laws of influence of the operating parameters on the transport characteristics of the core were analyzed. The results show that the drilling performance is related to the geometric parameters of the pipe and core, drilling speed, and depth. When the submergence ratio is increased to 0.9 , the maximum liquid-phase superficial velocity is increased by 109 % compared with that when the submergence ratio is 0.6. The size of the annular space gap 67 formed between the core and the pipe wall is the key to the core's mechanical properties, and the differential pressure gradient force increases with increasing core diameter. An increase in well depth reduces the fluid flow. In addition, increasing the pipe diameter improves drilling performance due to reduced friction losses, which elevates the air flow rate required for air-lift reverse circulation operation. [ABSTRACT FROM AUTHOR]

Rapid development of the anomalous enhancement of separated turbulent Re = 6000 air flow and heat transfer in an in-line single-row package of 31 inclined grooves, 0.2 in dimensionless depth, in a singled-out longitudinal region of the wall of a narrow channel is studied. It is due to the interference of vortex wakes behind the grooves and the acceleration in the channel flow core with the formation of a zone of ultrahigh longitudinal velocity. The wave-shaped parameter characteristics are stabilized in the region of approximately 15th groove, whereupon the oscillation amplitudes are moderately reduced. The return flows in the grooves are enhanced with distance from the entry section, the minimum negative friction diminishing from −2 to −4. The total relative heat removal from the structured region increases at q = const by a factor of approximately 2.75 and by the factor of two at T = const with increase in the relative hydraulic losses by the factor of 1.7, as compared with the case of a plane–parallel channel. The relative heat removal from the surface bounded by the contour of the 20th inclined groove amounts to 3.7 (q = const) with increase in the hydraulic losses by the factor of 2.2. An increase in the local maximum of the longitudinal velocity up to a factor of 1.5, as compared with the mean-mass velocity, can be observable. [ABSTRACT FROM AUTHOR]

Ventilation, carried out using centrifugal fans, is essential for obtaining good quality ambient air. Its role is to satisfy hygiene and comfort needs. It aims in particular to provide fresh air, in order to allow the proper functioning of the various devices, to evacuate air polluted by various pollutants and to combat humidity and condensation. In this context, the objective of this work is to study the internal flow of humid air for different concentrations in a fan rotor using the ANSYS-CFX software, based on the finite volume method. Flow turbulence is taken into account using the k-Ε model. The scientific contribution in this field consists of showing that the concentration of humid air has a considerable effect on the properties of the flow such as: pressure, shear stresses and flow speed which is in agreement with the results of experimental studies. This study can be used to locate the area's most exposed to this change in flow properties and which will result in premature damage to the blades by erosion and a reduction in fan efficiency. It will therefore be possible to take preventive measures to minimize the harmful effects of humidity concentration on centrifugal fans. [ABSTRACT FROM AUTHOR]

In the process of water filling in long-distance water transfer projects, the transient flow of water and air, along with the fluctuation in pressure, indicates the complexity of the hydraulic transition process, particularly when there are curved pressurized pipes, and the movement of air inside the pipes is not easily determined. This study focuses on pipeline systems with significant changes in elevation, such as those crossing rivers or roads. It employs a combined approach of generalized model experiments and numerical simulations to investigate the formation and transformation of flow patterns in the pipeline system during the filling process. It also analyses the fluctuation of pressure on both sides of the curved pipe under different filling modes and reveals the coupling mechanism between the movement of large-scale air bubbles and turbulent vortex structures within the curved pipe. When the water filling velocity at the pipeline inlet is v = 0.8 m s–1, the size of the bubbles formed by the air is larger, the variety of flow patterns is greater, and the evolution of flow patterns is more complex. When impounded water occurs in the river crossing pipeline due to maintenance, the pipeline system forms slug flow at a filling flow velocity of v = 0.8 m s–1. This leads to an abrupt change in the overall pressure of the pipeline system, with the maximum pressure being 1.36 times that of the filling flow velocity of v = 0.4 m s–1. At a filling flow velocity of v = 0.8 m s–1, bends in the pipe readily foster the formation of large-scale bubbles. The interaction between the buoyancy and drag forces acting on these bubbles and the centrifugal forces provided by the bends results in continuous changes in the hydraulic conditions within the pipe. The research findings not only enrich the study of the hydraulic transition process in pipeline systems but also hold significant importance for expediting the construction pace of long-distance water transfer projects. [ABSTRACT FROM AUTHOR]

Loss of tail rotor effectiveness (LTE), also known as unanticipated yaw, has been recognized to be a major contributing factor in several helicopter accidents due to the loss of directional control. Flight tests have identified specific wind azimuth regions that may alter the angle and the speed of the airflow through the tail rotor leading to LTE. Through the helicopter flight data monitoring (HFDM) program, pilots receive constant flight evaluation reports to support LTE risk mitigation. Nevertheless, the existing LTE safety metric presents several pitfalls that hinder the reliability of the detection of violations of boundaries for flight safety. To identify the appropriate methods to properly simulate and flag LTE events and develop a more comprehensive and reliable LTE safety metric to be used within the HFDM environment, a physics-based investigation of the different LTE flight characteristics is performed. The results from this investigation are expected to contribute towards an improvement in detection of LTE events, leading to a reduction in LTE-related accidents. [ABSTRACT FROM AUTHOR]

• A novel system is proposed to utilize LNG cold energy in cascade. • Thermodynamic and economic analyses are carried out for the proposed system. • The system is compared to other systems in the same field for performance evaluation. • The round-trip efficiency of the proposed energy storage system is 138.81 %. For cutting down the energy consumption and improving the cold energy conversion efficiency of the traditional liquefied air energy storage system (LAES), a novel energy system integration solution is proposed by combining the LAES with liquefied natural gas (LNG) regasification process. In this paper, the principal energy storage and energy release processes are simulated by Aspen Hysys. The influences of air mass flow rate and LNG regasification pressure on the performance are analyzed. The results indicate that the introducted system can attain 137.82 % round-trip efficiency, which is about 20 % higher than the conventional LAES system. Besides, the energy capacity reaches up to 10.87 MW and the exergy efficiency is 39.58 % during long-distance transportation. It's noteworthy that the power output in the liquefied air energy discharging period far exceeds the power generation from the organic Rankine cycle. The higher LNG transport pressure, the worse LNG-LAES system performance. When the air mass flow rate raises from 40,000 kg/h to 64,000 kg/h, the exergy efficiency is 3.4 % higher than the original, while the round-trip efficiency decreases by 29.79 %. Finally, through economic viability calculations, the dynamic recovery period of the LNG-LAES system is 5.41 years. [ABSTRACT FROM AUTHOR]

Heat dissipation performance is crucial for the operational reliability of industrial equipment, which can be monitored by detecting the wind or airflow temperature of the radiator. The emergence of triboelectric nanogenerators (TENGs) provides new routes for wind energy harvesting and self‐powered sensing. Herein, a rotary wind‐driven triboelectric nanogenerator (RW‐TENG) with soft‐contact working mode is newly designed to achieve tunable contact areas by utilizing the reliable thermal response of NiTi shape memory alloy (SMA) to air/wind temperature. The RW‐TENG can generate different triboelectric outputs under air stimulation with different speeds or temperatures, which is demonstrated as a power source for online monitoring sensors, self‐powered wind speed sensing, and airflow temperature monitoring. Specifically, a self‐powered sensor of wind speed is demonstrated with a sensitivity of 0.526 µA m−1 s between 2.2 and 19.6 m s−1, and a self‐powered monitoring device of high airflow temperature, which show relatively short response time (109 s), strong anti‐interference ability and outstanding long‐term durability. This study introduces an innovative route for real‐time detection of airflow temperature in wind‐cooled industrial equipment, showing broad application prospects for information perception and intelligent sensing of the industrial IoTs. [ABSTRACT FROM AUTHOR]

An unmanned underwater vehicle (UUV) powered by a compressed air power system is proposed to address challenges for battery/motor-powered vehicles under high-speed navigation, long endurance, and high mobility. These vehicles actively utilize supercavitation drag reduction by the exhausted gas from the compressed air power system. MATLAB/Simulink and FLUENT are used to establish theoretical models of the compressed air power system and ventilation supercavitation. The relationship between system power and navigation resistance is examined with different air flows, along with a comparison of endurance of different power vehicles at various speeds. The issue of the endurance-enhancing effect of supercavitation at high speed is investigated. The results demonstrate that increasing the air flow leads to higher power and reduced navigation resistance, and there is a balance between them. Furthermore, compared to the battery-powered vehicles with equal energy storage capacity, the compressed air power system shows 210.08% to 458.20% longer endurance times at speeds of 30 kn to 60 kn. Similarly, considering equal energy storage mass, it achieves 42.02% to 148.96% longer endurance times at high speeds (30 kn to 60 kn). The integration of supercavitation and air-powered systems can greatly enhance the endurance and maneuverability of the vehicle at high speeds while ensuring a compact system structure. The investigations could offer valuable ideas for the development and application of compressed air power systems for UUV at 30 kn to 60 kn or higher maneuvering. [ABSTRACT FROM AUTHOR]

Exposure to UV-A light was paired with low RH air flow for the dehydration of both mango and apple. Control samples of each were dehydrated with the low RH air and no UV-A light in order to determine the significance of the UV-A light in the dehydration process. The control mango contained approximately 85% more moisture wet basis than the UV-A light–dehydrated samples which resulted in approximately 91.4 ± 4.5% of the original mass of water being removed. The control apple contained approximately 55% more moisture wet basis than the UV-A light–dehydrated samples which resulted in approximately 96.0 ± 0.1% of the original mass of water being removed. The preservation of the physical and chemical integrity of the UV-A light–dehydrated samples was confirmed using electron microscopy and infrared spectroscopy analyses even after prolonged storage at a wide range of RH levels (11.3–86%). The thermal properties associated with certain physical properties of the samples were analyzed using a differential scanning calorimeter, confirming the preservation of the physical integrity of the samples. Despite not having any pretreatments for enzyme inactivation, the UV-A light–dehydrated mango and apple samples preserved much of their original color as compared to the control samples. [ABSTRACT FROM AUTHOR]

The microclimate environment can be conveniently controlled with accuracy by plant incubators, in which the cuttings propagation method can efficiently enhance seedling production. To ensure air flow evenly throughout the incubator, the scientific design of the air inlet is crucial. This study utilized a computational fluid dynamics (CFD) model to simulate the airflow patterns in a culture layer under different air inlet conditions. Furthermore, the optimal design parameters were determined by way of response surface methodology (RSM) and the Non-dominated Sorting Genetic Algorithm-II (NSGA-II). Adopting the optimal parameters, a prototype was manufactured, and a cuttings experiment was carried out with apple cuttings in the incubator. The results showed that the optimal air inlet radius is 90 mm, the optimal air inlet height is 188 mm, and the optimal uniform flow plate hole diameter is 13 mm. Meanwhile, the apple cuttings were able to root. Therefore, this incubator with optimal parameters can be used for cuttings. The study provides a methodological and theoretical basis for the future optimizing of air inlet parameters and promoting cuttings rooting. [ABSTRACT FROM AUTHOR]

In high-speed gear systems for aeroengines, reducing the fluid dynamic loss, which accounts for the majority of power loss, can significantly improve fuel economy. However, few practical numerical examples are available regarding high-speed gas-liquid two-phase flows involving gear meshing and gear shrouds (gear enclosures, which are effective for loss reduction). Therefore, in this study, the porosity method for object boundaries including the gear meshing, the volume of fluid method, and the surface compression method for the gas-liquid interface was used as fast and numerically stable calculation methods. In addition, a gap was provided at the contact surface of the gear tooth surface to improve the calculation stability, and the oil properties were set considering the difference between the flow resistance in a two-phase flow and that in a single-phase flow (due to the separation of oil particles) to improve the calculation accuracy. To validate the numerical simulation method, a two-axis helical gearbox with a maximum peripheral speed of 100 m/s with specifications equivalent to aeroengine gears was used, and the air flow, oil flow, and fluid dynamic losses were validated. Once the practical accuracy was confirmed, the numerical simulation was used to understand the relationship between air and oil flows, torque, and the effect of the shroud. Consequently, the fluid dynamic loss could be classified phenomenologically. [ABSTRACT FROM AUTHOR]

Wind speed is an important variable in the assessment of thermal comfort. Different types of meteorological devices provide different accuracy of air velocity (va) measurements, which under limited air flow conditions, may result in a discrepancy in actual thermal stress level. Simultaneous measurements on warm summer days, performed with a cup anemometer and hot-wire probe, prove that too high starting threshold of the first of these sensors can lead to a discrepancy of actual wind speed, and as a consequence can distort MRT (estimated with globe thermometers) and PET values on average up to 10 °C and 1 °C, respectively. [ABSTRACT FROM AUTHOR]

The existing grape drying technology and equipment often have problems such as poor hygiene conditions, high drying costs, and large drug residues. Therefore, the market urgently needs grape drying equipment with low energy consumption, high efficiency, and a green-clean processing process. To solve the above problems, a piece of integrated drying equipment combining the two technologies of air impingement blanching and air impingement drying for multi-layer grape material drying is designed. The dried product quality is directly affected by the airflow field distribution. Therefore, obtaining good airflow distribution and airflow velocity uniformity in the drying chamber via parametric studies is essential to ensure uniform drying of products. Since parametric and optimization investigations by physical experiments are usually expensive and time-consuming, computational fluid dynamics (CFD) being a flexible and less expensive tool can be employed to perform such studies. In the current work, the airflow velocity distribution and uniformity of the drying material room are analyzed by Ansys Fluent software. The airflow velocity non-uniformity coefficient is used to evaluate airflow uniformity. Results show that the original design has poor uniformity and needs to be optimized. The influence of air inlet chamber deflection device and material truck airflow baffles on the flow field of the material drying room is investigated to improve the uniformity of airflow distribution. Considering drying efficiency and uniformity, drying material room structure with the addition of deflection device design with the structural parameters of L = 50 mm and θ = 76°, airflow baffle design with the structural parameters of h = 0 mm, θ2 = 20° is chosen as the final optimized design. After optimization, the velocity of airflow between material layers has improved overall, and the maximum difference of average airflow velocity between material layers has been reduced from 0.73 m/s to 0.69 m/s, improving the drying uniformity of dried materials. In comparison to other drying equipment, the current integrated drying equipment combing air impingement blanching and drying has the advantages of being efficient and energy-saving, suitable for large-scale drying of grapes with better drying quality. The current results could guide the drying equipment design for grapes and develop the grape drying industry with high-dried quality. [ABSTRACT FROM AUTHOR]

In this paper, an attempt has been made to analyze the effect of different physiological conditions i.e., rest, moderate and extremely active on the branch Reynolds number, pressure drop, lost work, alveolar partial O2 pressure, airway resistance and surface tension. From the analysis, it has been observed that local Reynolds number and tracheal pressure drop along with the generations of branch. The alveolar O2 pressure and surface tension decrease with the increased activity level. Work lost due to different major and minor losses in the respiratory tract increases with the increase in activity level. A similar trend was also found for the airway resistance i.e., increases with the increase in activity level. A new parameter, Breathing Work Number (BWN) in respiratory mechanics is introduced. BWN is the ratio of the work of breathing to the sum of work of breathing and work loss, which might find a significant application to denote the respiratory health. From the analysis, it is found that BWN decreases with the increase in activity level. [ABSTRACT FROM AUTHOR]