Spray Angle Research Articles

Numerical Prediction on In-Cylinder Mixture Formation and Combustion Characteristics for SIDI Engine Fueled with Hydrogen: Effect of Injection Angle and Equivalence Ratio

Although their ease of transport, storage, and use makes hydrocarbon fuels dominant in commercial energy systems, the emission of harmful gases, including greenhouse gases, is a fatal disadvantage. Despite ongoing research to improve thermal efficiency and reduce the emissions of internal combustion engines using conventional hydrocarbon fuels, achieving net-zero carbon requires decarbonizing fuels rather than reducing the use of internal combustion engines. Hence, transitioning away from hydrocarbon fuels and evolving internal combustion engines into clean engines using carbon-free fuels, such as hydrogen, is necessary. This study designs a 2.0 L research engine and numerically analyzes its combustion characteristics and spray behavior by varying the spray angle and equivalence ratio. When comparing the turbulence kinetic energy at a 45-degree spray angle with that at 30 degrees and 60 degrees, on average, there was a difference of approximately 37.54 m2/s2 and 26.21 m2/s2, respectively. However, misfires occur in the lean condition. Although hydrogen has a wide flammability range, poor mixture formation under lean conditions can result in misfires. The 60-degree spray angle resulted in the highest combustion temperatures and pressures for all equivalence ratio conditions, consequently leading to the highest emissions of nitrogen oxides. Specifically, at a lambda value of 2.5, the 60-degree spray angle emitted approximately 29 ppm, 0 ppm, and 161 ppm of nitrogen oxides for each respective spray angle.

Study of Internal Flow in Open-End and Closed Pressure-Swirl Atomizers with Variation of Geometrical Parameters

This study delves into the examination of internal flow characteristics within closed (with nozzles) and open-end pressure-swirl atomizers (lacking nozzles). The number of inlet channels “n” and the opening parameter “C” were manipulated in this study, as they play a pivotal role in understanding various atomizer attributes, such as uniformity of the air-core diameter, the discharge coefficient, spray angle, and more, all of which hold significance in the design of bipropellant atomizers for liquid rocket engines (LREs). To validate our findings, six distinct hexahedral meshes were generated using Ansys ICEM software 2023. Subsequently, we employed Ansys Fluent, considering the RNG k-ε turbulence model and the VOF (volume-of-fluid) multiphase model to identify the liquid–gas interface, to aid in analyzing the uniformity of the air core, which is directly linked to the even distribution of mass, the mixing ratio of propellants, combustion efficiency, and stability. The results indicate that the uniformity of the air core is not solely contingent on an increase in parameter “n” but is also influenced by an increase in the parameter “C”. It is worth noting that the key dimensions of these six atomizers were determined using a mathematical model based on Abramovich and Kliachko theories.

Exploring heat transfer efficiency in non-boiling spray cooling

Spray cooling today is one of the most effective methods for high heat flux application. Since there are numerous factors influencing the heat transfer in spray cooling, some issues related to the effect of the nozzle-to-surface distance, heat flux and liquid subcooling on the heat transfer efficiency in non-boiling mode remain debated. This study is dedicated to a comprehensive experimental investigation of the impact of various factors, including the distance from the nozzle to the heater (2–35 mm), heat flux density (up to 6.9 MW/m2), liquid flow rate (8.8–25.2 mL/s), and initial liquid temperature (20 and 80 °C) on heat transfer in non-boiling spray cooling using different nozzles with varying spray angles (30–90°). Heat transfer results were obtained based on field temperature measurements using high-speed infrared thermography. It is shown that the nozzle-to-surface distance has a significant effect on the spatial distribution of the temperature field and the heat transfer rate in spray cooling. It is shown that for each nozzle and heating surface there is an optimum distance at which the maximum heat transfer rate at non-boiling spray cooling is observed and relationship for their determination are proposed. The heat transfer coefficient for deeply subcooled liquid (80 K) is practically independent of the heat flux. At low subcooling levels (20 K), the heat transfer coefficient increases with the increase in heat flux associated with the influence of evaporation from the liquid film surface on the total heat transfer. The results obtained are analyzed, compared and generalized with data from the literature, and a correlation is proposed for determining the heat transfer in non-boiling spray cooling.

Exploring thermal dynamics and porosity of cold-sprayed Ti-6Al-4V coatings on Al6061-T6 substrates: A pulsed thermography and numerical modeling approach

In this investigation, we use pulsed thermography and a multilayer analytical model to critically evaluate the thermal diffusivity and inherent porosity in cold-sprayed Ti-6Al-4V coatings on Al6061-T6 substrates. These coatings are of importance in deploying cold spray as an additive manufacturing technique for the restoration of high-cost alloy components. Our study draws upon experimental data obtained at spray angles from 50°to 90°, illustrating the relationship among the spray angle, porosity within the coating, and the resultant thermal diffusivity. Our results reveal a decrease in porosity and an increase in thermal diffusivity as the spray angle increases from 50°to 90°. In conjunction with our experimental approach, a numerical model was developed, incorporating binary images derived from optical micrographs to simulate transient heat diffusion during pulsed thermography experiments. The congruence between our empirical findings and simulation data affirms the effectiveness of the applied methodology, shedding light on the complex interplay between processing parameters and the resulting thermal properties. This study explores the effects of porosity and thermal gradients introduced during pulsed thermography, providing a profound understanding of the thermal dynamics of cold-sprayed coatings.

Multifunctional Biological Properties and Topical Film Forming Spray Base on Auricularia polytricha as a Natural Polysaccharide Containing Brown Agaricus bisporus Extract for Skin Hydration

Mushrooms are edible fungi containing valuable nutrients. They provide attractive bio-active properties, which have confirmed anti-oxidants, anti-aging, and anti-inflammatory properties. Mushrooms possess abundant natural polymers affecting skin hydration and acting as moisturizers supporting skin barrier function. In this study, cloud ear mushroom (Auricularia polytricha) water extract (CW) was produced as a natural polymer to evaluate a new film-forming spray (FFS) containing CW to increase skin hydration and protect transepidermal water loss. CW contained polysaccharides as 748.2 ± 0.02 mg glucose/g extract. CW significantly inhibited the secretion of IL-6 and TNF-α and enhanced skin hydration by increasing aquaporin-3 (AQP3) and filaggrin (FLG) in HaCaT cells. The FFS was formulated using CW, sodium polystyrene sulfonate, and glycerin. The selected formulation contained brown Agaricus bisporus (BE-FFS) evaluated physical appearance, spray angle, spray pattern, and in vitro skin permeation. The BE-FFS has a transparent thin film with suitable occlusive properties, drying time, and physical appearance. Afterward, in vitro skin permeation and human hydration property studies presented the long-lasting effects and provided safety and hydration potential after 4 weeks of use. Overall, all results indicate that the BE-FFS is a natural film-forming spray for skin hydration improvement.

Using Computation Fluid Dynamics to Determine Oil Droplet Breakup Parameters during Emulsion Atomization with Pressure Swirl Nozzles

A wide range of commercial powdered products are manufactured by spray drying emulsions. Some product properties are dependent on the oil droplet size, which can be affected by fluid mechanics inside the spray nozzle. However, most of the key flow parameters inside the nozzles are difficult to measure experimentally, and theoretical estimations present deviations at high shear rates and viscosities. Therefore, the purpose of this study was to develop a computational model that could represent the multiphase flow in pressure swirl nozzles and could determine the deformation stresses and residence times that oil droplets experience. The multiphase flow was modelled using the Volume-of-Fluid method under a laminar regime. The model was validated with experimental data using the operating conditions and the spray angle. The numerically calculated shear stresses were found to provide a better prediction of the final oil droplet size than previous theoretical estimations. A two-step breakup mechanism inside of the nozzle was also proposed. Additionally, some of the assumptions used in the theoretical estimations could not be confirmed for the nozzles investigated: No complete air core developed inside of the nozzle during atomization, and the shear stress at the nozzle outlet is not the only stress that can affect oil droplet size. Elongation stresses cannot be neglected in all cases.

Exergy and energy analysis of a novel solar powered fog desalination system

A novel system that applied fogging as a desalination technique was recently published, which could be considered a further development of the humidification-dehumidification desalination system (HDH), that provides an advantage through its ability to desalinate high salinity levels. This involves spraying hot saline water at high pressure vertically upwards, creating a mist instead of large water droplets. This increases productivity since the fine mist facilitates evaporation and the low-saline mist can go upwards more than the large high-salinity droplets. However, experiments showed that this methodology, in terms of productivity, performance and cost, was between other technologies. It was noted that the performance of this system peaked at ~39 %. Therefore, in this paper, an exergy analysis of the system is presented to determine the location of the highest exergy destruction and also highlight its comparative feasibility. The results indicated that the exergetic efficiency of the system reached 17.3 % while the main source of irreversibility is the fogging process itself (~75 %). Additionally, increasing the water temperature from 33 to 76 °C increased the exergetic efficiency of the fogger from 4 % to 20 %. Therefore, the authors recommend using a combination of humidification and atomization via nozzles of larger orifices with different spraying angles.

Material characterization and inter/intra-particle validation for DEM simulation of urea coating process

Particle coating is a common operation in the controlled-release fertilizer (CRF) industry, where a coating layer is appliedto the urea cores. A discrete element method (DEM) computer simulation was applied to model the coating process for the urea granules using measured model parameters. The accuracy of DEM input parameters for the coating material properties and the physical and mechanical characterizations of urea granules are crucial to the study of particle coating processes. Thus, to enhance the simulation accuracy, information on the material properties (urea granules) is required. In this study, the elasticity parameters, shear modulus, coefficient of restitution (CoR), and coefficient of rolling and static friction (CoRF) and (CoSF) of urea granules are estimated experimentally in addition to the physical characteristics. The sensitivity of the angle of repose of the urea bed was investigated at different coefficients of friction. According to the obtained experimental value of the angle of repose, values of 0.2 and 0.3 for CoRF and CoSF, respectively, were adjusted to obtain consistent urea granules’ motion for simulation and the experiment. Moreover, the spray droplet sizes and velocity distributions were estimated using the video-imaging process technique. Based on this experimental characterization, elasticity parameters and spray properties were integrated into DEM simulation software as input data to perform numerical analysis of the coating process to compare simulation and experimental results, which show uniformity at three different pan speeds with a maximum deviation of 0.033 at 5 rpm. Also, consistency between DEM and experiment results was achieved in terms of average coating thickness (μm) of the selected samples and average intra-particle thickness variation (CoVintra). These results revealed that the coating film thickness is proportional to the rotation speed for the experiment and simulation. To enhance the inter-particle coating uniformity, the effects of the most significant parameters such as pan speed, filling ratio, particle size, spray rate, and spray angle, were examined. A low spray rate, filling ratio, and high pan speed improved the coating uniformity. The particle size and spray angle show considerable influence on the coating uniformity, where larger particle sizes and spray angles tend to reduce the inter-particle coating uniformity.

Study on atomization mechanisms and spray fragmentation characteristics of water and emulsion butachlor.

Agricultural chemicals are commonly used to control pests and weeds, but cause pesticide waste problems. Oil-based emulsions are often used as pesticide formulations to improve pesticide utilization. In this study, the spray visualization experiment of the water and oil-based emulsion butachlor is carried out using an ST flat fan nozzle at 0.1-0.5 MPa pressure. The dimensionless method is used to analyze the difference in liquid sheet fragmentation morphology and disintegration process and the influence of different fragmentation methods on droplet size. It is found that the hydrophobic components in pesticide have a significant effect on the morphology and process of atomization fragmentation. When spray liquid is water, the liquid sheet breaks up into liquid ligaments due to the Rayleigh instability, then the ligaments break up into droplets. The side view of a liquid sheet is a large-amplitude wave disturbance. When the spray liquid is the emulsion butachlor, holes are generated on the liquid sheet, then the holes break up into droplets. The fragmentation method of emulsion spray is the perforation mechanism. Compared with water spray, the presence of the pesticide butachlor increases the droplet size and spray angle and improves the uniformity of droplet size distribution but reduces the breakup length. The spray angle shows a power law dependence of the Weber number with a power of 0.17 for all conditions tested here. At 0.3 MPa, DV50 increases 25%, and span decreases from 1.187 to 1.172. This study could provide reference for the addition of agricultural additives, the improvement of spray operation efficiency, and the establishment of spray fragmentation mechanism.

Aerodynamic effect on atomization characteristics in a swirl cup airblast fuel injector

To investigate the influence of swirling air flow field on the spray characteristics and the droplet behaviors of the swirl cup airblast fuel injector, a single swirler cup and a double swirlers cup airblast injector were operated in a wide range of fuel mass flow rates (mf) and relative air pressure drops (ΔPa). Various laser based diagnostics, including planar Mie scattering, phase-Doppler particle analyzer, and high speed particle imaging velocimetry, were employed to provide the information of spray angle, droplet Sauter mean diameter (SMD), droplet velocity, and air flow velocity. The results show that the air flow field was characterized by central toroidal recirculation zone (CTRZ), the double swirlers cup airblast injector generated stronger CTRZ than single swirlers cup airblast injector. The spray characteristics and the droplet behaviors with different size classes were significantly affected by the air flow field. The larger droplets (25–100 μm) with higher initial momentum were likely to keep its velocity when passing through CTRZ, when the mf increased, more large fuel droplets could pass through the CTRZ and expanded to both sides, resulting an increase in a spray angle. On the other hand, smaller droplets (<25 μm) with lower initial momentum were trend to be enrolled by the CTRZ; therefore, the spray droplets at lower mf were confined in the CTRZ. These droplets trend to coalesce with each other resulting in an increase of SMD in this region.

Effect of high-frequency jet velocity perturbations on impinging jets atomization characteristics

The atomization characteristics of impinging jets with high-frequency jet velocity perturbations is studied numerically based on the volume of fluid method. Three typical perturbation modes are considered to mimic the velocity discrepancies of jet flow in real engine conditions. Both the perturbation amplitude and frequency are investigated independently. Results show that the liquid sheet structure and atomization characteristics are significantly changed under the intrinsic perturbation frequency. The spectrum analysis is performed to reveal the specific phenomenon and explore the mechanism of different velocity perturbation modes. The analyses show that the atomization process is sensitive to perturbation frequency but its effectiveness diminishes significantly at excessively high frequencies. Additionally, when the frequency of velocity perturbation approaches the natural intrinsic frequency of sheet waves, resonance occurs within the liquid sheet for certain perturbation mode, leading to dramatic varies in breakup length and spray angle because the velocity superposition of the intrinsic and perturbed flow and its dynamics.

Effect of water injection on the cooling performance of flame deflector in rocket engine testing platform

Ground test is an essential step to ensure the reliability of the design and assess the quantity and performance of rocket engine. However, supersonic and high-temperature rocket exhaust gas directly impinging on the flame deflector of test platform cause severe heat damage which brings about a low repeated utilization and construction cost of the deflector. Generally, the water is employed as the coolant for the spray cooling system to protect the flame defector of test platform. In this paper, Euler-Euler approach is adopted to investigate the multi-phase flow in a flame deflection of rocket engine test platform. An evaporation model based on concentration difference is chosen to simulate the mass and heat transfer between water injection and exhaust plume. Model validation shows that the predicted results are in good agreement with the experimental data. The effect of water injection, including spray location and angle, and mass flow rate, on the afterburning and cooling performance of flame deflector is numerically investigated. The results show that the afterburning of exhaust plume could be inhibited by the water injection. In terms of maximum and area-averaged temperature on the bottom and inclined surfaces of flame deflector, the configuration with spray nozzle angle of 60° has the lowest area-averaged temperature. For the simulated cases with different spray nozzle diameters, the difference of maximum and area-averaged temperatures is below 11.0 K and 6.1 K, respectively. In addition, the maximum and area-averaged temperatures increase first and then decrease with the increase of spray nozzle diameter.

The properties of sustainable aviation fuel I: Spray characteristics

This study measures the spray penetration, spray angle and spray volume of sustainable aviation fuel (SAF) experimentally using an optical constant volume combustion chamber under different ambient temperatures, injection pressures, and ambient pressures. The results show that when the ambient temperature increases from 200 °C to 300 °C, the spray penetration decreases by ∽10%–20%, while it further decreases by ∽40%–50% when the temperature increases from 300 °C to 400 °C. Furthermore, the spray penetration of SAF will reach its stable stage fastest at 400 °C. As the ambient temperature increases, the spray angle and spray volume of SAF decreased by 10%–20% and 50%, respectively. In addition, the spray penetration and spray volume of SAF increased by 10% and 20%, respectively, with an increase in injection pressure at 200 °C. An increase in injection pressure at 400 °C causes the decrease in spray penetration and spray volume of SAF by 20%, and both of them showed increasing and decreasing trends at the stable stage. Thus, increase in injection pressure has little effect on the spray angle. Moreover, the spray penetration and spray volume of SAF showed a decreasing trend on increasing ambient pressure, but significant effect was observed at a high temperature of 400 °C than at a low temperature of 200 °C. Conversely, the spray angle of SAF showed an increasing trend with an increase in ambient pressure, but this influence was larger at a low temperature of 200 °C than that at a high temperature of 400 °C.

Design and combustion characteristics analysis of a static shaft turbofan engine

Abstract A design scheme of a static shaft turbofan engine is proposed to meet the requirements of light weight and large thrust weight ratio of small aeroengine. As the core component of stable combustion, the thermal protection problem of the mid-mounted combustion chamber is particularly prominent. This paper designs a mid-mounted combustion chamber configuration that combines gas film cooling and central combustion. The influence of structural parameters on combustion characteristics is explored by numerical simulation, and the theoretical design and numerical simulation is verified based on combustion test results. The results show that the flame shape of the mid-mounted combustion chamber conforms to the characteristics of central combustion. The combustion effect of the nozzle with spray angle of 45° and flow rate of 1.87 kg/h meets the requirements of secondary combustion of the static shaft turbofan engine, and the air inlet of the combustion liner effectively increases the thickness of the cooling gas film. The experimental results are in good agreement with the numerical simulation results, and the temperature of the combustion liner wall can be reduced effectively. The above research provides a theoretical basis for the combustion chamber design of small static shaft turbofan engines and a reference for the thermal protection methods of small aeroengine combustion chambers.

Effect of nozzle geometry on combustion of a diesel-methanol dual-fuel direct injection engine

A three-dimensional model of fuel combustion in a diesel-methanol dual-fuel direct injection engine is constructed to study the effect of nozzle geometry. The model includes two nozzles, one for diesel injection and one for methanol injection. Based on the geometric modeling and empirical formulas for the nozzle, the influence of fuel flow in the nozzle on fuel combustion in the cylinder is calculated. In the geometric modeling, the influences of the R/D and L/D parameters on the effective injection radius of the nozzle, the spray velocity at the outlet, and the fuel’s Sauter mean diameter in the cylinder are analyzed. For the flow simulation inside the nozzle using empirical formulas, the effects of discharge coefficient and spray angle are analyzed. The simulation results show that a larger R can increase engine power. Both R and L have an impact on the formation of pollutants. The discharge coefficient has a greater impact on the performance of the engine than the spray angle, and a suitable spray angle is around 13°. The effects of dual-fuel nozzles with different diameters on combustion temperature and pollutant emissions in the engine cylinder are analyzed through experiments.

Investigation of flow characteristics and mixing of liquid hydrogen within a premixing swirl tube for the turbine engine combustor

This article explores the flow characteristics and fuel mixing in a premixed tube leading to the combustion chamber, focusing on hydrogen fuel. A CFD simulation utilizing a discrete phase model (DPM) was conducted to investigate the impact of spray angle, spray pressure, and fuel-to-air ratio on fuel atomization, fragmentation, and fuel-air mixing efficiency. The findings highlight the critical role of the spray angle in fuel atomization and breakup. Increasing the spray angle enhances atomization, resulting in smaller fuel droplet sizes and improved fuel-air mixing. The particle diameters ranged from 165 μm to 117 μm for spray angles of 15°–60°, respectively. Additionally, spray pressure significantly influences particle diameter, velocity, and turbulent kinetic energy. Higher spray pressures promote efficient atomization, fragmentation, and smaller particle sizes, enhancing fuel dispersion and mixing. The fuel-to-air ratio also plays a crucial role, with lean mixtures (0.0003 kg/s of fuel flow rate) facilitating increased fuel-air mixing and smaller droplet sizes. Furthermore, the swirl motion induced by airflow and lower fuel-to-air ratios enhances fuel atomization and breakup, resulting in finer spray characteristics. These insights contribute to optimizing spray angle, pressure, and fuel-to-air ratio, ultimately improving fuel injection systems, combustion efficiency, and emissions reduction across various applications.

Experimental Investigation on Gasoline—Water Mixture Fuel Impingement Preparation Method and Spray Characteristics with High Injection Temperatures and Pressures

Gasoline–water mixed injections are of great interest because of their advantages for reduced manufacturing costs and improved atomization, with the potential to alleviate engine detonation and reduce emissions. In this work, based on the principle of impinging flow, a real-time gasoline–water mixture preparation system for internal combustion engines was designed and the preparation system performance was compared with the standard swirl mixing technique. An image processing method was established to quantify the uniformity of the prepared mixture. Based on the flash-boiling spray flash-boiling spray experiment, the spray characteristics of different gasoline–water mixtures were analyzed under different injection temperatures (30–160 °C) and pressures (5–15 MPa). The experiments showed that the impinging pressure was the main factor affecting the emulsification performance of the real-time gasoline–water mixture, and that the proposed real-time mixing system could produce a stable gasoline–water emulsion. For temperatures in the 30–160 °C range, the flash-boiling spray flash-boiling spray experiments showed that the spray penetration distance first decreases and then increases with the injection temperature, while the spray angle shows an opposite trend. The turning point corresponded to the flash-boiling point of each gasoline–water mixture.

A New Modeling Method for Spray Angle Prediction of Liquid–Liquid Pintle Injector

Accurate predictions of the spray angle play a significant role in the design and operation of the pintle injectors. However, existing prediction models are often based on idealized assumptions and expressed as the functions of the jet-to-film momentum ratio corrected by different coefficients, which result in the weak generalization abilities of these models. In the present study, a prediction model for the spray angle of the liquid–liquid pintle injector was established and verified. The initial interactions between the radial jet column and the axial jet film were considered, and the deflected trajectory of the transverse jet column was derived theoretically; then, the spray angle of the pintle injector was thus obtained. Specially designed experiments were carried out, and the spray angles were extracted by using high-speed photography. The comparisons between the experimental and the predicted results clearly exhibit the limitations of the traditional models that are based on the momentum ratio only, and they prove the accuracy of our new model.

In searching of optimum electrospray ionization using both spray image and electric current measurement

Electrospray image and spray electric current measurement were used to experimentally characterize the optimum operating condition of the electrospray ionization process under different operating conditions, including electrospray flow rate (Q), solution electric conductivity (k) and the organic solvent content in the sample solution (Ro). It was first observed that a special cone-jet mode electrospray with extremely high stability could be obtained when the electrospray voltage was operated in a specific range (the optimum voltage range). In this mode, the spray current remains independent of spray voltage and the angle of electrospray (the optimum spray angle) was much larger than the ones in other modes of electrospray. The experimental results also showed that the optimum voltage range was dependent on multiple factors. The average value of the optimum voltage range (the optimum voltage) increased slightly as Q was increased and decreased significantly as Ro was increased. In addition, the optimum voltage would increase initially with the increase of k and become essentially independent of k at a sufficiently high solution electric conductivity. In contrast to a rather complicated parametric dependence of the optimum voltage range, the optimum spray angle was found to only depend on Q. It would increase initially as the increase of Q and remain to be constant when Q was higher than a specific value. The experimental results in this study allow one to maintain an optimum electrospray ionization under different operating conditions as required by the actual method of mass spectrometry analysis.

Ethanol Blend Effects on The Spray Properties of a Biodiesel Fuel by Ambient Pressure Variation

Diesel engine spray nozzles are crucial to pollutant generation and engine efficiency. Nozzle performance can be enhanced by adjusting the nozzle's internals. A successful demonstration of the nozzle would be one in which the spray's outcome was uniformly dispersed throughout a wide area, with the grains scattered similarly. The purpose of this research was to examine how a diesel-ethanol characteristic under normal atmospheric pressure (spray tip penetration, the velocity of spray, and spray angle) and, in general, to assess the performance of biodiesel fuel on diesel engines, a substantial amount of biodiesel and operational expenses for the engine are necessary. It was an experimental approach to the study. The research involved recording spray fuel at the nozzle. Using a 480 fps high-speed camera, we tested BD20, BD20E5, and BD20E10 fuel at three different ambient pressures (1 bar, 2 bar, and 3 bar). The injection pressure was 15 MPa, and the fuel temperature was 28.2 degrees Celsius. Spray tip penetration and spray velocity decreased and spray angle increased after ethanol was added to the mixture, consistent with the studies' findings. Lowered spray tip penetration, slower spray speeds, and a complete spray angle result from the increased ambient pressure.