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The atmospheric pressure pulsed microwave He plasma jet has the advantages of high electron density and abundant active particles, but its shrinking on the discharge electrode morphology limits its application range. In order to modulate a He plasma jet with a longer plume and study its ionization development characteristics, we constructed a dual-channel pulsed microwave coaxial discharge device. He and air were, respectively, injected into the inner and outer gas channels of the resonator to generate a double-layer atmospheric pressure microwave plasma jet with a longer plume. It is observed that the bifurcation of the stratified plasma jet will occur by changing the gas flow. The ionization development of plasma jet was observed by using enhanced charge-coupled device and microwave Rayleigh scattering apparatus measured the space-time evolution of plasma and observed the three times ionization enhancement process of plasma jet development. The spectral lines of the active products associated with Penning ionization were observed by using a fiber optic spectrometer. A fluid model was constructed to simulate and analyze that under the condition of sufficient He flow rate (He flow rate is above 0.6 slm), there will be sufficient and stable He mole fraction (64%) at the stratification of the plasma jet. The experimental and simulation results show that the jet profile of the microwave He plasma is related to the inlet structure of the discharger and He flow rate. Stratified intake structure can produce stratified He plasma jet, and the unique appearance of bifurcation of jet can be produced by changing the flow rate of He. In the bifurcation process of the plasma jet, the product of Penning ionization inhibits the development of the main branch of the plasma jet, and the secondary electron avalanche of the local electric field promotes the formation of the branch of the plasma jet and is accompanied by the enhancement of the second ionization. The ionization mechanism of microwave He plasma is the resonance excitation of local enhanced electric field, the advance of ionizing waves, and the interaction between the spatially distributed active particles. [ABSTRACT FROM AUTHOR]

We present a new food processing method to increase the content of polyphenols, which are a type of health-promoting food component, in harvested onions using atmospheric-pressure low-temperature plasma technologies. Harvested onions were locally irradiated for different times with a low-temperature air plasma jet generated near atmospheric pressure and stored in the dark for various periods. The plasma-irradiated area was 7 mm2. The plasma irradiation was performed without removing the onion peel. After storage following plasma irradiation, the onion was peeled and cut into the outer, middle, and inner parts, analysing polyphenol content at each edible onion part, namely the bulb. The polyphenol content in the onions irradiated for 30 min and stored for 3 d increased over that of unirradiated onions stored for the same period. This increase occurred regardless of the bulb parts. Neither the plasma-irradiated onions without storage nor the air gas-irradiated onions without air plasma irradiation exhibited a higher polyphenol content. In particular, quercetin aglycone, quercetin 4′-O-glucoside, quercetin 3-O-glucoside, and quercetin 3,4′-O-glucoside were increased in the polyphenol content, contributing to an increase in the antioxidative activity. NO3− and NO2− were introduced into water under an onion peel by air plasma irradiation for 30 min and decreased after 3 d of storage but remained. However, no H2O2 was introduced. The plasma-introduced NO3− was distributed throughout the onion owing to the plasmodesmata serving as channels for cell-to-cell transports of molecules. These results suggest that the increased polyphenol content originates from the transcriptional factors acting in stress responses to the plasma-introduced NO3− and NO2−, not the electric field-induced electroporation, in onion cells. The present study provides valuable insights into interactions between low-temperature air plasma jets and onion cells. [ABSTRACT FROM AUTHOR]

We conduct an experimental investigation on the implementation of cat-ear-shaped film cooling holes for thermal protection in a hydrogen-air rotating detonation engine (RDE). The rotating detonation combustor adopts a cylindrical configuration with 390 cat-ear-shaped film cooling holes densely distributed over its outer wall. We successfully achieve ignition and self-sustained propagation of the rotating detonation wave (RDW) under film cooling conditions, resulting in the RDE producing a supersonic outflow via a Laval nozzle installed at the exit. During operation of the film-cooled RDE, the introduction of cooling air through the film cooling holes leads to an increase in the static pressure of the combustor, and potentially causes up to a 15% variation in RDW propagation velocity, depending on the main flow-based equivalence ratio and the mass flow rate of cooling air. The effect of film cooling on the thrust performance of the RDE is analyzed, and additional cooling air is found to result in an increase in thrust. Periodic blockage of film cooling holes occurs due to RDW propagation, causing an elevation in static pressure within the cooling air chamber. Additionally, as the RDW sweeps across the film cooling holes at a high frequency along the tangential direction, cooling air jets deflect, resulting in distinctive burned traces in areas relative to their proximity to the film cooling holes. • Experimental study on cat-ear-shaped film cooling holes for thermal protection of RDE. • 390 cat-ear-shaped cooling holes densely distributed on a cylindrical RDE's outer wall. • Successful ignition and self-sustained RDW achieved under film cooling conditions. • High-frequency RDW causes periodic blockage and deflection of cooling air jets. [ABSTRACT FROM AUTHOR]

The local heat transfer characteristics of circular multiple air jet impingement on semicircular concave surface were studied experimentally. For constant Reynolds number (Re = 9,000), the effect of jet to concave surface spacing (z/d = 1, 4.2, 6), ratio of curvature (D/d = 4.28, 6, 8.6), jet-to-jet spacing (s/d = 2.4, 4, 5.6), and number of jets were considered. The local heat transfer characteristics were determined by using infrared thermal camera and thin foil method. Lower curvature value ratio (D/d = 4.28) resulted higher average heat transfer coefficient due to broader spread of heat transfer distribution, whereas higher curvature ratio (D/d = 8.6) resulted in lower average heat transfer coefficient due to steeper heat transfer distribution in the stagnation area. At lower D/d, z/d, and s/d with seven jet configuration, the heat transfer coefficients were found effective as compared to other configurations due to broad heat transfer distribution and less interaction between the jets. At given D/d and s/d configuration, the stagnation Nu at θ = 0° do not coincide with jet hole center axis and this shift is more pronounced at higher z/d value. This could be due to additional push before jet impinging on concave surface. The secondary peaks were observed between two neighboring stagnation regions in Nu distribution along the center longitudinal line for lower z/d and higher s/d values. This resulted due to upwash that was obtained from jet interactions related to collisions with the wall jets. The correlations of stagnation line average Nu and overall average Nu were obtained. The coefficient of variance of local heat transfer coefficient for each configuration was determined, and correlation was proposed to analyze the degree of non-uniformity. [ABSTRACT FROM AUTHOR]

The study investigates the efficacy of plasma-activated water (PAW) in preserving green chillies (jalapeño and pusa jwala) and compared it with various household fruits and vegetables cleaners' solutions. PAW was prepared using a pencil plasma jet with air as the plasma forming gas. The results of visual analysis revealed that PAW-treated chillies maintain their fresh appearance even after 21 days, exhibiting significantly lower spoilage compared to control (ultrapure milli-Q water) and fruits and vegetables cleaners' solutions. PAW demonstrated antimicrobial properties, effectively reducing microbial growth and spoilage on chillies over the storage period. Physical attributes, such as weight loss and firmness, are evaluated. It has been observed that PAW-treated chillies exhibit lower weight loss and higher firmness, indicating better membrane integrity and moisture retention. Microbial resistance was notably higher in PAW-treated chillies compared to control and when cleaning solutions were used. CIELAB color analysis revealed that PAW-treated chillies retain greenness, and color, freshness, outperforming control and cleaners. Sensory evaluation, including visual inspection, smell, taste, and touch, consistently favored PAW-treated chillies, emphasizing their superiority in terms of enhancement in shelf-life. Biochemical analysis revealed that PAW-treated chillies either maintain or show enhancement in nutritional attributes such as soluble sugar, protein, and ascorbic acid concentrations. Phenol concentration (antioxidant activity) remained stable across treatments. Overall, the study underscores the positive impact of PAW treatment on preserving the membrane integrity, antimicrobial resistance, sensory quality, and nutritional attributes of green chillies, making PAW an alternative for extending their shelf life. [ABSTRACT FROM AUTHOR]

This paper describes the synthesis of ZnO nanoparticles using air microplasma jets as the main reaction medium. Various techniques, including X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and UV—Vis spectroscopy, were employed to confirm the characterization of the artificially synthesized ZnO nanoparticles. The absence of additional peaks associated with secondary phases of ZnO, as revealed by the XRD analysis, indicates the exceptional purity of these nanoparticles. Through the use of SEM, we examined the surface morphology and observed a substantial rate of agglomeration. The energy band gaps of ZnO nanoparticles were determined to be 3.3 electron volts (eV). The cytotoxic effects of zinc oxide nanoparticles were assessed using the methyl thiazolyl tetrazolium (MTT) assay on breast cancer cells exposed to various doses of the nanoparticles. The Acridine-Orange/Ethidium-bromide (AO/EB) dual stain was employed to assess apoptotic cells. The data indicate that ZnO NPs can induce apoptosis, suggesting their potential as an anticancer treatment in breast cancer cell lines. The presented findings indicate that nanoscale zinc oxide particles (ZnO NPs) possess significant potential for future utilization in many biological applications. An example of such an application could be the prospective substitution for chemotherapy in the management of various forms of cancer diseases. [ABSTRACT FROM AUTHOR]

The scientific task of the nozzle scheme uses for formation of an air cushion by using the energy of a jet of air supplied under pressure, simultaneously to form an air cushion, as well as to create the driving force of a load-bearing web, was formulated and the main idea of the work was defined. The optimal option to significantly increase the productivity and length of special types of conveyors is to use the energy of a jet of air supplied under pressure simultaneously as an air cushion and as the driving force of the load-carrying body, which makes it possible to sharply reduce the coefficient of resistance to movement of the load-carrying body and improve its operating conditions. Supporting the load-carrying body with an air cushion allows to increase the speed of movement to 8 to 9 m/s and more, increase the reliability and safety of conveyor operation, and protect the environment. [ABSTRACT FROM AUTHOR]

In this study, the transient and steady-state heat transfer caused by an air jet impinging on a heated plate moving back and forth in the horizontal direction is investigated experimentally. The jet flow issuing form nozzle of various geometry (circular, triangle, square) is impinged on rough and smooth surfaces. In addition, Reynolds number (jet velocity), distance between the nozzle and the plate, plate velocity and stroke are considered as independent parameters that could affect the heat transfer.The optimum number of experiments is determined with the help of Taguchi design of experiment method. The transient and steady-state heat transfer are analyzed by means a high-technology thermal camera. Local and average Nusselt numbers representing the heat transfer characteristics are calculated in response to the variable parameters. Comparative graphs and ANOVA test results are presented and evaluated in order to determine the effects of parameters on heat transfer. As a result, it has been seen that Reynolds number (82%) is the most dominant parameter affecting heat transfer. Other parameters are listed as nozzle geometry (7.6%), surface roughness (4.9%), plate velocity (1%), stroke (0.6%) and nozzle-plate distance (0.1%) according to their degree of effect. [ABSTRACT FROM AUTHOR]

Heat transfer characteristics of two types of jet impingement, confined and unconfined is investigated using air and water as the working fluids. The effects of volumetric quality are evaluated on the lateral variation of the Nusselt number at low nozzle-to-plate spacing. The results show that the lateral Nusselt number of the unconfined submerged air bubble jet is similar to that of the confined submerged air bubble jet in Region I (bubble collision region) due to the effect of bubble collision. In Region II (bubble sliding region), however, the lateral Nusselt number of the unconfined jet was found to be 30%–40% lower than that of the confined jet flow due to the buoyancy effect that causes air bubbles to rise in Region I. In addition, from the flow visualization, high velocity bubble movement was observed from the midpoint of the heating surface to the periphery of the confinement plate in the confined jet set-up. This movement enhances the lateral Nusselt number in Region II. In the unconfined jet set-up, air bubbles rise past the heating surface in Region I and thus neither slide across the heating surface nor increase the lateral Nusselt number in Region II. [ABSTRACT FROM AUTHOR]

Copyright of Cotton Textile Technology is the property of Cotton Textile Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The burning in a two-section channel with an abrupt enlargement of its cross section in the process of double-belt supply of different-type gaseous fuels into it at a Mach number of the fuel flow M = 2.2 and at its stagnation temperature of 1700 K was numerically investigated. For the ignition of a hydrocarbon fuel fed into the channel along its axis (the first supply belt) and for the formation of a transonic regime of burning of the fuel, it was subjected to a gasdynamic pulse action, and, after this action was terminated, for the maintenance of the burning regime, the second belt of supply of a fuel (hydrogen or a hydrocarbon fuel) into the channel and the side supply of an air jet into it were organized. The Reynolds-averaged Navier–Stokes equations were solved with the use of the k–ε model of turbulence. The burning of a fuel in the channel was simulated by gross reactions. It was established that the use of hydrogen as a fuel in the second supply belt makes it possible to maintain the transonic burning regime in the channel. In this case, the side air jet breaks the shock-wave formation in the second section of the channel and, in so doing, provides a high-velocity homogeneous fuel flow in it. [ABSTRACT FROM AUTHOR]

Copyright of Industria Textila is the property of Institutul National de Cercetare-Dezvoltare pentru Textile si Pielarie and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In order to analyze the influence of a water medium on the forming process and penetration performance of a shaped charge jet, a comparative study was carried out on an underwater shaped charge jet (USCJ) and a shaped charge jet (SCJ) in air. The virtual mass hypothesis is proposed to analyze the forming mechanism of USCJs. The arbitrary Lagrangian–Eulerian algorithm is adopted to carry out a series of simulation calculations considering the impact of standoff height and liner cone angle. The penetration test of the shaped charge jet in two media is carried out, and the experimental results verify the effectiveness of the theory and simulation. The differences of SCJ formation and penetration in air and water are analyzed. The results demonstrate that the USCJ exhibits a higher jet head velocity, higher cumulative kinetic energy, and a greater penetration ability than those of the jet in air. The depth of penetration (DOP) initially increases and subsequently decreases with an increase in the standoff height. The optimal standoff height of the USCJ is approximately 4–4.5 times greater than the charge diameter, whereas the SCJ in air is approximately 3.5–4 times greater than the charge diameter. Additionally, the DOP of the jet decreases at the optimal standoff height with an increase in the cone angle. [ABSTRACT FROM AUTHOR]

In today's world, research on cooling systems that can effectively reduce the cooling time of heat sinks and enhance heat transfer efficiency in a shorter duration is extremely crucial. This experimental study analyzed the cooling time by simultaneously utilizing two cooling techniques. This involved the passage of ferrofluid (Fe3O4/water) through three channels of a heat sink under the influence of a magnetic field, as well as the application of an air impingement jet on the heat sink's surface. A novel plate-fin heat sink with dimensions of 40 mm (L) × 31.32 mm (W) × 23.5 mm (H) consists of three channels with a diameter of 3 mm for crossing ferrofluid flow and 24 channels on the top of the heat sink for crossing the air was designed and built for the study. The heat sink was exposed to an air impingement jet and an external magnetic field simultaneously. Multiple tests were conducted to determine the convective heat transfer coefficients of the heat sink over time under specific conditions, including a magnetic field of 800 G, a volume fraction of 3%, a Reynolds number of 600 for the ferrofluid, and a mass flow rate of 0.1 kg/s. It was discovered that using the combined method of magnetic field and impingement jet (MF-IJ) compared to cooling by air impingement jet with the simultaneous passage of pure water through the ferrofluid channels (Water-IJ), as well as the ferrofluid flow under a magnetic field without the impingement jet (MF) methods for the designed heat sink, can increase the maximum heat transfer coefficient by 27.4% and 46.4%, respectively. The findings of this study suggest that using the MF-IJ cooling method as a flow control mechanism, along with this innovative geometry, can reduce the cooling time of the heat sinks. [ABSTRACT FROM AUTHOR]

A cavity-flame holder is widely used for the injection of the fuel jet in a supersonic combustor due to high fuel residence time. This paper presents extensive results about the impacts of extruded annular multi-jets for improving fuel mixing inside the cavity flame holder. A three-dimensional model of the cavity with multiple extruded nozzles in different lengths and conditions has been examined in this study to investigate the flow and fuel mixing inside the cavity. In addition, the usage of internal air jets is investigated and extensive comparisons between the elongation of the extruded nozzle and the use of the inner air jets for better fuel distribution are done. The presented results show that the usage of both inner air jet and nozzle elongation significantly enhances the fuel distribution within the cavity flame-holder. The achieved finding confirms that the latter technique is more efficient for the fuel mixing in the combustor of a scramjet engine. [ABSTRACT FROM AUTHOR]

The present study on the brown seaweeds Sargassum muticum focused on the application of dehydration by pressing or pulsed electric fields (PEF) pretreatment before three drying processes, namely freeze-drying, air impingement drying, and natural convection in an oven. Both pretreatments permitted to reduce significantly the initial moisture of the seaweeds with a reduction up to 50 %. The structural modifications induced by these pretreatments had a direct impact on the mechanisms of moisture retention and distribution within the seaweeds, which consequently exerted an influence on drying kinetics. The apparent moisture diffusivity for freeze-drying was significantly improved by PEF passing from 2.98 10−9 m2 s−1 to 3.62 10−9 m2 s−1 after a total disintegration. Concerning oven drying by natural convection, a dehydration by pressing will be preferred because the drying time to reach 0.45 kg kg−1 in dry basis was reduced by 61 min with this pretreatment. [ABSTRACT FROM AUTHOR]

Utilization of inorganic waste, if included in composite material, can be beneficial in reducing the accumulation of waste, which could help in resolving problems of disposal. beside from that, incorporating waste into composite materials also reduces the overall cost of the composites as a whole. The study examines the impact of dolomite content on the mechanical properties of the composites. Increasing the amount of dolomite in the composite significantly weakens its flexural strength, falling from 42.4 MPa at 0 % dolomite to 28.7 MPa at 15 % dolomite. Composite tensile strength also decreases by up to 25.8 % with rising dolomite dust concentration. Additionally, dolomite increases interlaminar shear strength (ILSS), with EDH15 composites showing the highest improvement. Dolomite dust in epoxy‐based composites increases the hardness value from 85 HRL to 95 HRL with an increase in dolomite dust content. The erosion test perform on air jet tester shows lowest wear rate was achieved under the following conditions: 10 % dolomite dust weight, 30° impingement angle, 10 m s−1 impact velocity, and 150 μm erodent size. Furthermore, scanning electron microscopy was used to examine the damaged, eroded surfaces for assumed wear mechanisms. [ABSTRACT FROM AUTHOR]

In this work, three cooling strategies were proposed to increase the cooling rate and avoid extensive exposure to higher temperatures during the manufacturing of components in Inconel 625 using wire arc additive manufacturing (WAAM): forced cooling with compressed dry air jet, interpass idle time and the combination of both strategies. These strategies were compared for two welding technologies within gas metal arc welding (GMAW) process: pulsed and cold metal transfer (CMT). The results show that deposition using the GMAW-CMT welding mode showed better quality and uniformity than the GMAW-pulsed mode. The tested interpass idle time did not cause a significant effect on the mechanical properties, while the forced cooling using an air jet slightly improved the properties and may be used to increase productivity, especially for larger components. [ABSTRACT FROM AUTHOR]

The research focuses on the high-load compressor cascade with a four-tooth straight-tooth labyrinth seal. Jet holes with varying air inlet and jet positions are designed to investigate the mechanism and principles underlying the impact of adaptive jets on the performance of compressor cascades. The results show that the jet flow from the labyrinth seal to the suction side has a good improvement effect on the performance of the compressor cascade, which can suppress the influence region of the concentrated separation vortex and the wall vortex, improve the flow field structure, reduce the total pressure loss, and enhance the expansion capacity. What is more, the improvement effect on the flow field structure and the performance is enhanced as the flow rate of the jet hole increases. The most significant improvement in the performance of the compressor cascade is achieved by introducing air from the second tooth cavity, which can reduce the total pressure loss coefficient by 3%, reduce the volume of low kinetic energy fluid clusters by 9.48%, and significantly enhance the performance of the compressor cascade. [ABSTRACT FROM AUTHOR]

The existence of defective drilled lotus seeds will lead to problems such as plumule residue and lotus seed appearance damage, which decreases the quality of lotus seed food products. Therefore, it is vital to sort drilled lotus seeds. Since the drilled holes on defective seeds are not coaxial with the axis of the lotus seeds, blowing an air jet along the axial direction towards the end face of defective seeds will generate a different acoustic response than that of qualified ones. Based on this characteristic, this study proposes an intelligent sorting method for drilled lotus seeds based on air jet impact acoustic signal and one-dimensional convolutional neural network (1D-CNN) acoustic classification. The method directly extracts features from 1D acoustic signals and achieves automatic classification through the constructed 1D-CNN. First, the sorting principle, acoustic signal data acquisition and preprocessing, and dataset preparation methods were introduced. Then, the effect of hyper-parameters, including the number of convolutional layers, convolution kernel size, learning rate, and training epochs, on the performance of the 1D-CNN model was investigated. On this basis, the parameters were optimized to form the final 1D-CNN model – AudioLS (Audio of Lotus Seed). The accuracy, detection time, and parameters achieved by AudioLS were 98.04%, 25.12 ms, and 0.79 M, respectively. Compared with five classic 2D-CNN models, i.e., Residual Network (ResNet) 50, Visual Geometry Group (VGG) 16, VGG19, DenseNet121, and Extreme Inception (Xception), AudioLS achieved better performance. The accuracy increased by 1.82%, 1.30%, 1.28%, 1.83%, and 2.05%, respectively, and the detection time was shortened by 16.77%, 2.71%, 7.85%, 28.11%, and 11.92%, respectively. The research results verify the effectiveness of the proposed intelligent sorting method. [ABSTRACT FROM AUTHOR]

This article is dedicated to diagnosis of damage to air distribution in a room with twisted, compact, and flat air jets, and to searching of ways to solving the problem. It was found that in order to avoid damage to the air distribution system in rooms of different purposes and dimensions; it should be air streams of the appropriate types and with the appropriate characteristics. Parameters of a swirled, compact, flat, rectangular air jet when creating comfortable climatic conditions in the rooms of different purposes and dimensions are determined. The relationship between the angle of inclination of the rotating plates (for twisted jets), ratio of sides of the slit (for all rectangular including compact and flat streams) and a long-range of these flows is established. [ABSTRACT FROM AUTHOR]

In order to cope with the frost damage problems that occur in cold-region tunnels, the engineers have proposed the measure of setting up a heated air curtain at the tunnel entrance. In this paper, a three-dimensional transient heat transfer numerical model was first established to calculate the temperature distribution of the tunnel under the natural wind, which has a good agreement with field test data. The insulation effects of the heated air curtain were demonstrated, and effects of five factors, namely, temperature (Tn) and speed (Sn) of the natural wind, speed (S), temperature (T), and angle (A) of the jet airflow of the air curtain, were discussed. Then, an orthogonal test sensitivity analysis was conducted on the operating parameters (T, S, and A). Finally, effects of the air curtain were predicted by neural networks. The results show that the use of air curtains can effectively shorten the length of the negative temperature section of the tunnel structure. Low temperatures and large speed of the natural wind will weaken the effects of the air curtain. In the two cases, the operating parameters of the air curtain require adjustment according to demand. Increasing S and T can effectively enhance insulation effects. And the optimal A is between − 15° (toward inside the tunnel) and 0°. The sensitivities of the influences of the three operating parameters on the insulation effects are ranked as T (2.142), S (1.832), and A (0.77). The prediction results of the neural network indicate that using Tn, Sn, T, S, and A to predict the length of the negative temperature section (Lv) and temperature of the tunnel vault surface (Tv) is feasible and efficient. This research can provide a reference for the application of air curtains as anti-freeze measures in cold-region tunnels. [ABSTRACT FROM AUTHOR]

This work investigates the performance of modified tungsten carbide inserts when turning supermartensitic stainless steel with cutting fluid and/or air jet applied in two directions: either cutting fluid under high pressure or compressed air under low pressure supplied on the back of the chip (through a hole produced near the principal cutting edge), together with either cutting fluid or compressed air, both under low pressure, directed at the clearance face. Tool performance is evaluated by means of the principal cutting force, temperature distribution (using FEM), visual evaluation of the rake face, morphology of the chips and the quality of the machined surface. The findings indicate that the groove reduces the cutting force when dry cutting. Cutting fluid applied under low pressure at the clearance face is more efficient in decreasing both the cutting force and chip temperature than cutting fluid at high pressure supplied at the back of the chip. A chrome oxide layer is formed on the chip when air jet is applied, thus leading to an unfavorable cutting condition. The simultaneous application of cutting fluid under high pressure to reach the back of the chip and compressed air supplied through the clearance face provides the best surface quality. [ABSTRACT FROM AUTHOR]

The formation of red plasma diffuse jets (PDJs) initiated by a capacitive discharge in air at pressures of 0.1–10 Torr is studied. Data on the dimensions and properties of plasma diffuse jets including counter-propagating ones with different and identical front polarities are obtained in a pulse-periodic discharge mode in a 15-cm-diameter tube. Photographs of the discharge glow in various modes are presented. It is confirmed that the emission of counter-propagating PDJs is suppressed at the same polarity of voltage pulses. It is shown that during a collision of unipolar PDGs formed from two generators the brightness of the discharge plasma between the ring electrodes increases. [ABSTRACT FROM AUTHOR]

The bactericidal components of air plasma jets generated by a direct-current glow discharge and a dielectric barrier discharge were studied using IR and UV absorption spectroscopy. The mole fractions of bactericidal components with an absorption spectrum band structure were determined by selecting a mole fraction value in the calculated spectrum that ensured correlation with the experimental spectrum. The spectra were calculated using the HITRAN spectral database and the Specair 3.0 program. The error in the mole fractions due to violation of the Bouguer–Lambert–Beer law when using absorption coefficients convoluted with the instrument function was determined. The mole fractions of bactericidal components with a continuous absorption spectrum were calculated using the Bouguer–Lambert–Beer law in a standard way. IR and UV absorption spectroscopy were shown to enable determination of the mole fractions for the full set of bactericidal components in air plasma jets of glow and barrier discharges. [ABSTRACT FROM AUTHOR]

The study focused on examining the area-averaged heat transfer characteristics of an air jet impinging on a concave surface. The experiments involved varying the Reynolds number (Re) within the range of 10,000 to 75,000, while adjusting the jet-to-plate distance from 3 to 20 times the jet diameter (d). The experimental setup included a jet with a diameter of 11.5 mm, and concave surfaces with curvature radii of 218 mm (Curvature ratio (Cr) = 0.026) and 281 mm (Cr = 0.021) were used. A detailed investigation was conducted using Infrared Thermography to measure the average Heat Transfer Coefficient (HTC) of jet impingement on these concave surfaces. The aim was to assess the impact of surface curvature on heat transfer at different locations from the impingement point. Additionally, the research compared the heat transfer effects in circular and square impingement regions that were identical in radial span and area ratios. It was observed that the area-averaged Nusselt number (Nu) generally increased with a higher Re and a lower jet-to-plate distance ratio (z/d). A maximum average Nu increase is observed for Cr = 0.026 when the mass flow rate is from 10,000 to 75,000. Increasing the curvature is an effective approach to provide localized cooling. A correlation comparison was also conducted, and a new empirical correlation has been proposed. This correlation works effectively across various ranges of Re, z/d, Cr, and radial position (r/d) with a deviation of less than ± 11%. [ABSTRACT FROM AUTHOR]

The present work deals with the experimental and numerical study of steadystate conjugate heat transfer during impingement of turbulent air jet over a heated stainless steel. The plate is heated using copper heater located at the middle. The temperature field is measured using an infrared camera and compared with the numerical simulations. Numerical simulations are performed using three-dimensional finite volume based formulation. The turbulence shear-stress transport (SST) is modeled using k-ω model based on the Reynolds averaged Navier Stokes (RANS) equations. The numerical simulations are in good agreement with the experimental data with marginal discrepancy in the steel plate region due to the contact thermal resistance between steel and copper. It is observed that the local Nusselt number increased in the stagnation region with increasing velocity of the impinging turbulent flow and practically unaltered in the region of the steel plate. [ABSTRACT FROM AUTHOR]

During the operational ventilation process of high-altitude helical tunnels, the installation method of jet fans is a key factor in determining the ventilation efficiency of the tunnel. In this study, the CFD numerical simulation method is adopted to establish three-dimensional ventilation models of helical tunnels with different curvature radii. Through orthogonal experiments, the effects of tunnel curvature radius on the characteristics of the air jet flow field, under the coupled influences of factors such as lateral spacing of jet fans, vertical height of fans, longitudinal spacing, and lateral offset, are investigated. The results show that when R = 500 m, 600 m, 700 m, and 800 m, the longitudinal spacing has the most significant impact on ventilation efficiency, followed by vertical height, with lateral offset and fan spacing having the least impact. The optimal spacing and vertical height of the fan groups remain consistent under different curvature radii, at 1.25D (fan diameter) and 15 cm, respectively. The optimal longitudinal spacing of the fan groups is 90 m, 90 m, 135 m, and 90 m, respectively. Shifting the fan groups 0.25 to 0.75 m towards the inner side of the tunnel helix (for R < 700 m) can optimize the flow field distribution within the tunnel. Finally, expressions for the relationship between the helical radius and the lateral offset and longitudinal spacing of the fan groups are established for the optimal installation parameters of fan spatial positions under different helical tunnel radii. [ABSTRACT FROM AUTHOR]

Climate actions have been gaining prominence in discussions about the industrial future due to the need to reduce the amounts of residual pollutants in manufacturing processes. Although the grinding process is widely applied in the industry for its finishing capabilities and dimensional and geometric precision, it is significantly polluting and detrimental to workers' health. This is attributed to the quantity of mineral oil used in conventional flood lubrication-cooling systems. With these demands in mind, this work proposes alternative methods by comparing the performance of the alumina grinding wheel with the conventional method of lubrication-cooling using MQL, with and without the WCJ auxiliary system, and distinguishing the direction angles of the air jet in the cylindrical grinding process. The workpieces are made of VP50 steel, and the analyzed output parameters include surface roughness (Ra), with confocal microscopy used on the workpiece surface, roundness error, diametrical wheel wear, G-ratio, grinding power, tangential cutting force, and cost and pollution analysis. [ABSTRACT FROM AUTHOR]

This study aimed to apply a portable pulsed cold air plasma jet (PP-CAPJ) device in onychomycosis treatment and investigate its effect and mechanism of action. Based on the characteristics of onychomycosis, we selected Trichophyton rubrum (T. rubrum) for our experiments and explored the inactivation ability of the PP-CAPJ on T. rubrum that grew in nails. We found that the PP-CAPJ could effectively kill T. rubrum in the nails, and for T. rubrum in 1.5 mm thick nails, 300 spark discharges could kill almost all the fungi. The fungicidal mechanism is mainly due to the ability of shock waves from the PP-CAPJ to impose pressure on the nail and destroy the cell membrane of T. rubrum. This work has therefore demonstrated the use of an effective and noninvasive approach for the treatment of onychomycosis. [ABSTRACT FROM AUTHOR]

The importance of fuel mixing for the progress of the scramjet engine is indisputable. The present article shows the importance of the non-equal multi-injector system for effective fuel distribution and flame holding inside the combustion segment of a scramjet engine. The supersonic air and fuel jet flow in the non-equal nozzle arrangement is simulated via computational fluid dynamic technique. Two injector types of circular and rectangular nozzle have been analyzed to attain flow characteristics of hydrogen jets at supersonic cross flow. Mach contour is also analyzed for these jet arrangements to show the interface of the jet in the non-equal jet arrangement. Besides, addition of internal air jet is also simulated and evaluated in this research. Our investigation shows that the diffusion height of the fuel jet is higher when a rectangular non-equal nozzle is applied. The circular nozzle is more active in the spreading of the fuel in the combustor and the use of an internal air jet effectively increases fuel in a combustor of the scramjet. [ABSTRACT FROM AUTHOR]

Much of the literature available on heat transfer enhancement from rough surfaces concerns flat plates or channels. Studies on protruding concave surfaces are surprisingly rare though they have the potential to enhance heat transfer. Therefore, three-dimensional steady-state simulations and corresponding experimental validation is carried out for an air jet impinging on a concave surface projected with semi-spherical protrusions. By providing multiple protrusions, various geometrical configurations are studied by considering the dimensions, angular positions, and pitch between the protrusions. Each individual configuration has its own unique flow pattern which makes prediction of heat transfer complex. This motivates present study to consider entire geometrical parameters affecting heat transfer characteristics with the help of networking tool. Past investigations on protruded flat surfaces concerns random allocation of protrusions. Hence artificial neural network is employed in this study to easily predict the corresponding heat transfer value with set of few input data. Simulation results give detailed flow physics which helps in understanding the heat transfer behavior. It is observed that each protrusion is marked with high-pressure region around its uphill and negative pressure around the downhill. As the flow moves downstream, the protrusions obstruct the flow path and flow separates away as soon as it reaches center of the protrusion. A maximum heat transfer enhancement of 11% is obtained over a corresponding smooth surface. [ABSTRACT FROM AUTHOR]

The incorporation of bioactive glass (BG) into zirconia-based composite materials shows a feasible option to enhance the biological properties, reduce the sintering temperature, and resist the transformation of the tetragonal phase of zirconia. In this present work, the bioceramic composites, having the general formula [(100-x) (8 Mg-PSZ) – x (13–93 BG)] where x = 0 to 25 wt%, have been prepared and evaluated the effect of BG amounts on the machinability, mechanical and biological behavior of the composite material. The machining experiment is performed on an abrasive air jet machine (AAJM), and machinability is evaluated in the form of material removal rate (MRR), surface roughness (SR), and mechanics of material erosion (MME) at room temperature. The machinability results show that MRR decreases with enhancing the BG contents, and the SR follows the opposite trend of MRR. The MME indicates that the material is removed from the surface mainly due to the erosion crater and brittle fracture. Further, mechanical properties are evaluated, and it is found that the inclusion of BG frits and sintering temperature is substantially associated with the relative densities and the mechanical characteristics. Adding BG reinforcements increases the mechanical characteristics at lower sintering temperatures (1250 °C) while reducing the mechanical characteristics except hardness at higher sintering temperatures (1350 °C). Elastic modulus decreases with the addition of BG content up to 15 wt%; after that, it slightly increases up to 25 wt%. The in-vitro bioactivity and bio-degradation are tested in simulated body fluid (SBF), and both are increased by enhancing the BG contents up to 25 wt%. The in-vitro cell culture is performed on the MG-63 cell line. The biocompatibility increases with BG concentration (up to 25 wt%). Based on experimental results, it may be concluded that 8 Mg-PSZ/13-93BG bioceramic composites may be a potential choice for biomedical applications. [ABSTRACT FROM AUTHOR]

Copyright of Diamond & Abrasives Engineering is the property of Zhengzhou Research Institute for Abrasives & Grinding and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This research focuses on utilizing numerical simulation to analyse how modifications in the air jet diffuser shape impact the cooling efficiency of electronic parts. The main aim of this study is to understand the physical and thermal mechanisms involved in the process. The study consists in numerically predicting the physical and thermal field of a cubic-shaped obstacle placed in the centre of a square subjected to a resulting flow field created by a transverse flow and a perpendicularly oriented impacting jet. The computations were done at a Reynolds number of 3 410, analyzing three perpendicular impinging jets with the ratio of impinging and cross flow Reynolds numbers α = Rej/ReH having the values of 0.5, 1, and 1.5. The k–ω SST turbulence model was used in this investigation. The effectiveness of the methodology that was put into action was evaluated by referring to the findings derived from the experiments conducted by Masip and his team. Once the methodology was validated, we studied the effect of changing the geometric shapes of the impinging jet diffusers on the cooling efficiency. Three geometrical shapes of air diffusers were tested (circular, swirling and lobed). We noted that there is a direct correlation between flow morphology and cooling efficiency. The impact of the ratio α was analysed and found to have a significant effect on the cooling efficiency. As this ratio increases, the quantity of heat transfer increases in all three air jet diffuser cases. In relation to the lobed air jet, it was observed that the Nusselt number exhibits greater values when compared to the other air jet diffuser cases. Moreover, it was noted that the lobed air jet diffuser can enhance the heat transfer efficiency for α = 1.5 by more than 16.3 % compared to the circular air jet diffuser. [ABSTRACT FROM AUTHOR]

The air permeability of the fabric is affected by the type of yarn used, the loom speed, and the amount of air pressure delivered by the relay nozzles. In this study, 21 Ne of ring and rotor spun yarns were used as a weft in an air jet loom. Loom speed and left- and right-side relay nozzles pressure in a range of 400–600 RPM, 2–4 bar, and 3–6.5 bar, respectively, were taken as additional factors. To develop and analyze the experiment, a full factorial design was used. It was observed that the air permeability of rotor spun weft yarn fabric's is greater than ring spun weft yarn fabrics. Furthermore, when the speed of the loom increased and the left- and right-side relay nozzles air pressure decreased, the fabric's air permeability increased and vice versa. [ABSTRACT FROM AUTHOR]

Jet impingement is a promising cooling mechanism to increase the rate of heat transfer in solar air collector. However, the effects of an impinging air jet on the exergetic performance of a bifacial photovoltaic-thermal with different packing factors are entirely unclear. In this research, a jet impingement bifacial photovoltaic-thermal solar air collector was developed and its exergetic performance was assessed. Jet plate reflectors with different geometric configurations are proposed to enhance the cooling and light absorption at the rear part of the bifacial photovoltaic module. Additionally, the link between exergetic performance and each variable's design and operational characteristics was examined through indoor experiments. The results showed that the maximum exergy efficiency of the bifacial photovoltaic-thermal with packing factor of 0.66 and 36-hole jet plate reflector has 11.88% under solar irradiance of 900 W/m2, and mass flow rate of 0.025 kg/s. The maximum exergy input, exergy destruction, and improvement potential of the proposed system are 402.81 W, 345.62 W, and 304.78 W, respectively. [ABSTRACT FROM AUTHOR]

This study presents a new pneumatic air jet excitation nozzle, specifically designed for food processing applications. The device, which uses compressed air equipment and a precision solenoid valve, controls air discharge through a parametric air jet nozzle. Tests showed that the device could achieve shooting frequencies in the 40–45 Hz range, with operational pressures between 5 and 7 bar. A sensor system was used to measure the force generated by the device at different frequencies and pressures. Using the Design of Experiments (DOE) methodology, we identified optimal cavity designs for 5 and 6 bar pressures. These designs outperformed others in generating uniform force and maintaining consistent vibration voltage behavior. This highlights the efficacy of our approach in enhancing device performance under different conditions. The device's practical application in food processing was demonstrated, particularly in delicate tasks such as the selective harvesting of sensitive crops like coffee fruits. The precise vibrations generated by the device could potentially enhance harvesting efficiency while significantly reducing mechanical damage to plants. The results position the device as a compelling proof of concept, offering an alternative method for exciting biostructures in food processing. This device opens up new possibilities in agricultural and biological fields, providing a non-intrusive and practical approach to manipulating and interacting with delicate, contactless structures, with a specific focus on improving food processing efficiency and quality. [ABSTRACT FROM AUTHOR]

An issue related to the application of portable smoke and heat removal devices for buildings and structures is to provide for their effectiveness when removing smoke and reducing temperature. That us why the object of this study was a change in the performance of a portable smoke and heat removal device when using finely sprayed water. Improved efficiency of the use of portable smoke and heat removal devices was based on experimental studies. It was proved that the reduction of smoke concentration and temperature in the room to the initial conditions was achieved for independent smoke dispersion in 5340 s, and cooling occurred in 3120 s. With the use of a smoke and heat removal agent during air supply, the smoke dissipated in 720 s, and cooling took 1560 s. And with the simultaneous supply of air and a sprayed jet of water, smoke dispersal occurred in 360 s, and cooling in 1020 s, respectively. To determine the efficiency of the smoke and heat release device, a calculation-experimental method has been devised that makes it possible to estimate the coefficient of the smoke and heat release agent when supplying air and water. According to experimental data, it was calculated that the coefficient of effectiveness of the smoke and heat removal devices when supplying air and water compared to the means when supplying only air increases by 2.1 times. The practical significance is that the results were taken into account when devising methodical recommendations for extinguishing fires. Thus, there are reasons to assert the possibility of targeted regulation of the processes of smoke reduction and temperature reduction through the use of a smoke and heat release device that simultaneously supplies air and finely sprayed water. [ABSTRACT FROM AUTHOR]

Numerical simulation of the underwater outflow of a supersonic overexpanded air jet is considered. The calculations are carried out in an unsteady three-dimensional formulation with a hybrid approach using Reynolds-averaged Navier–Stokes equations for nozzle flow and large eddy-simulation for jet flow. The calculation of the interaction of a gas with a liquid is performed with a volume of fluid, which takes into account the surface tension and compressibility of water. The structural features of turbulence when a supersonic air jet exhausted into water are analyzed. An unsteady formation of a supersonic jet and a gas cavity in a water is obtained, the shock-wave structure of the flow is visualized and the level of pressure fluctuations in water is reported. A comparison of the flow pattern when an air jet exhausted into air and water is made on a qualitative level. The results of numerical simulation of the jet velocity field are used to analyze the Kelvin–Helmholtz and Rayleigh–Taylor instability mechanisms and to reveal the dominant instability mechanism in different jet propagation regions. The results obtained are compared with experimental high-speed photographic recording data and numerical calculations At a qualitative level in literature. • LES of underwater outflow of a supersonic overexpanded air jet is performed. • CFD results are compared with experimental high-speed photographic recording data. • Jet instability mechanisms are analyzed. [ABSTRACT FROM AUTHOR]

In this work the combustion characteristics of liquid hydrocarbons when atomized by a high speed air jet were studied, using diesel fuel as an example. This approach to spraying liquid fuel in combustion processes has a number of advantages over traditional spraying: the ability to supply fuel with a low degree of purification, reducing the chance of coking of fuel equipment. Using an atmospheric burner device with natural air supply into the mixing chamber, the dependences of the composition of intermediate and final combustion products were studied, and the flame temperature was measured at various fuel flow rates and parameters of the atomizing air jet (flow rate, temperature). A comparison of the obtained characteristics was made for equivalent modes at different temperatures of the supplied atomizer. It was found that when heated air is used as a sprayer, higher flame temperatures are ensured, which ensures more complete fuel burnout and a decrease in CO concentration in the flue gases, but at the same time, a slight increase in NOx was observed. [ABSTRACT FROM AUTHOR]

Purpose: Material extrusion-based additive manufacturing is a prominent manufacturing technique to fabricate complex geometrical three-dimensional (3D) parts. Despite the indisputable advantages of material extrusion-based technique, the poor surface and subsurface integrity hinder the industrial application of this technology. The purpose of this study is introducing the hot air jet treatment (HAJ) technique for surface treatment of additive manufactured parts. Design/methodology/approach: In the presented research, novel theoretical formulation and finite element models are developed to study and model the polishing mechanism of printed parts surface through the HAJ technique. The model correlates reflow material volume, layer width and layer height. The reflow material volume is a function of treatment temperature, treatment velocity and HAJ velocity. The values of reflow material volume are obtained through the finite element modeling model due to the complexity of the interactions between thermal and mechanical phenomena. The theoretical model presumptions are validated through experiments, and the results show that the treatment parameters have a significant impact on the surface characteristics, hardness and dimensional variations of the treated surface. Findings: The results demonstrate that the average value of error between the calculated theoretical results and experimental results is 14.3%. Meanwhile, the 3D plots of Ra and Rq revealed that the maximum values of Ra and Rq reduction percentages at 255°C, 270°C, 285°C and 300°C treatment temperatures are (35.9%, 33.9%), (77.6%,76.4%), (94%, 93.8%) and (85.1%, 84%), respectively. The scanning electron microscope results illustrate three different treatment zones and the treatment-induced and manufacturing-induced entrapped air relief phenomenon. The measured results of hardness variation percentages and dimensional deviation percentages at different regimes are (8.33%, 0.19%), (10.55%, 0.31%) and (−0.27%, 0.34%), respectively. Originality/value: While some studies have investigated the effect of the HAJ process on the structural integrity of manufactured items, there is a dearth of research on the underlying treatment mechanism, the integrity of the treated surface and the subsurface characteristics of the treated surface. [ABSTRACT FROM AUTHOR]

The twin mountains, a common terrain in mountainous areas, tend to induce the acceleration effect under crosswinds, which enhances the wind speed and the turbulence performance of the flow field. To mitigate the impact of the acceleration effect on high-speed trains, structures, and aircraft near the twin mountains, this study investigates the effectiveness of the jet strategies, which are realized on natural mountain slopes by mechanical ventilation, with different jet angles on the flow field and the train. Wind speed tests, flow visualization, wind field prediction, and research on the train's aerodynamic behavior are conducted in this paper using the wind tunnel and the improved delayed detached eddy simulation dynamic models. The results indicate that the wind velocity on the leeward side of the twin mountains increases up to 1.42 folds of the wind velocity of the incoming flow under crosswinds. The jet streams with 0° and 30° angles are the most effective in mitigating the acceleration effect among those tested (0°, 15°, 30°, and 45°), reducing the maximum wind speed by 11.87% and 16%, respectively. Compared with the mitigation effect of the jet stream with the 30° angle, the jet stream with the 0° angle has a better mitigation effect on the aerodynamic loads (4.0%–13.2%) and its fluctuation amplitude (24.4%–42.7%) of the train. These findings are valuable for studying the flow field characteristics of the twin mountains and the designing anti-wind measures for high-speed railways. [ABSTRACT FROM AUTHOR]

Experimental research findings are reported on the characteristics of surface transformation of droplets of promising fuel slurries in the air, as they move at subsonic velocities typical of combustion chambers of power plants. The main components of the fuels were water, coal processing waste, and coal. Typical shapes of droplets and the duration of their deformation cycles were identified. Droplets containing more than 70% of the solid phase remained practically undeformed. The lowest relative velocities of droplets leading to their fragmentation were determined. The key characteristics of secondary droplets (their number, sizes, velocities, and surface area of liquid) were calculated on the basis of the experimental findings. These characteristics were compared with those of initial droplets. Disruption conditions in the chosen range of the gas jet pressure (P ≤ 6 bars) can only be provided for fuel slurry droplets containing less than 60% of a coal component. The effect of a group of factors on deformation characteristics was identified. These include air jet and droplet velocities, droplet sizes, temperature, concentration, and type of components and additives. Approximation equations were derived for the mathematical description of the experimental data. Using certain criteria, the conditions necessary and sufficient for the disruption of water–fuel slurries on impact with an air jet were estimated. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Engineering Transactions B: Applications is the property of International Journal of Engineering (IJE) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The latest technological advance in weaving machinery and preparation at 2022 China International Textile Machinery Exhibition & ITMA Asia were summarized. The structure and performance of weaving machinery were continuously optimized, the development was closer to the market demand. The manufacturing level of domestic rapier, air jet and water jet looms had developed rapidly, which improving the core competitiveness of household equipment. With the explosive growth of artificial intelligence, the digital transformation of weaving machinery was accelerated, the application of advanced information technology and automation tools were making the weaving machinery present a new trend of personalized, intelligent, green development. It is considered that weaving machinery has made remarkable progress in high speed, automation and greening in recent years. [ABSTRACT FROM AUTHOR]

An experimental study is conducted to determine the effect of chevrons with zero penetration angles at the CD nozzle exit on an emitted noise field. The implication of passive control is to reduce the blockage of the nozzle exit area with minimal engine thrust penalty. The cold air jets issued at design Mach numbers 1.5 and 1.75 from the De Laval nozzles of the circular section were investigated. This passive control eliminates screech tones at the over and ideally expanded conditions at 60° and 90° in the azimuth plane. The acoustic data measurements have also been observed for the chosen jet Mach numbers. The schlieren images reveal the shock cell pattern to eliminate the effect of shock-associated noise levels at supersonic jets. The results show that 10 chevrons with no penetration act as an effective eliminator of screech tone and noise suppression average ∆OASPL value up to 3 dB at Mach number 1.75. [ABSTRACT FROM AUTHOR]

Improvement of the fuel mixing inside the cavity flame-holder is important for the development of this injection system in scramjet engines. This article presents significant flow results on the mixing role of multi-extruded nozzles inside dual cavity flame holders with a single shock generator. A three-dimensional model of the dual cavity with injectors located on the inclined rear wall is produced to simulate real flow physics associated with proposed jet configurations. The impression of air injection from the inclined rear wall is also examined by computational modeling of the compressible flow inside the dual cavity. Based on the achieved results, the injection of multiple extruded nozzles enhances fuel diffusion in the cavity when the shock generator is applied. Our findings disclose that the injection of the fuel from the inclined rear wall results in more efficient fuel mixing inside the dual cavity flame holder. Mixing of the annular jet is increased about 14% via backward air jet inside the cavity. • Fuel mixing inside the cavity flame-holder is improved via dual cavity flame holders. • A three-dimensional model of the dual cavity with extruded injectors is simulated. • Fuel mixing and flame holding inside the dual cavity are investigated in the present work. • Injection of the fuel from the inclined rear wall results in more efficient fuel mixing inside the dual cavity flame holder. [ABSTRACT FROM AUTHOR]