Numerical investigation of gas/liquid two-phase flow in nozzle holes considering the fuel compressibility

Zhao, Jianhui; Liu, Weilong; Zhao, Jiaqi; Grekhov, Leonid

doi:10.1016/j.ijheatmasstransfer.2019.118991

Cited by 21 publications

(11 citation statements)

References 25 publications

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“…Sou et al experimentally studied the impact of nozzle design characteristics and consequently the inflow characteristics on the nozzle discharge coefficient . This verifies the computational findings, which shows that after cavitation occurred, the decrease in the discharge coefficient caused by the increase in the injection pressure becomes insignificant . Also, for a flow characterized by cavitation, the discharge coefficient is governed only by the cavitation number and it is almost constant …”

Section: Introductionsupporting

confidence: 87%

“…5 This verifies the computational findings, which shows that after cavitation occurred, the decrease in the discharge coefficient caused by the increase in the injection pressure becomes insignificant. 14 Also, for a flow characterized by cavitation, the discharge coefficient is governed only by the cavitation number and it is almost constant. 15 Nurick 16 experimentally illustrated that cavitation depends on the ratio of entrance curvature (r) to nozzle diameter (D N ).…”

Section: Introductionmentioning

confidence: 99%

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Prediction of the Impact of Nozzle Geometry on Spray Characteristics

et al. 2021

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In the present paper, the formation and development of cavitation inside the nozzle of an atomizer with different geometrical characteristics have been studied numerically. Different shapes of inlet nozzles and different nozzle-length-to-diameter ratios have been investigated. The developed model has been built as a three-dimensional (3D) one, where the turbulence is modeled considering large eddy simulation. The obtained computational results showed good agreement with the reported experimental results. It has been found that the occurrence of cavitation depends on the amount of energy needed to overcome the viscosity and friction between the liquid layers. The mass flowing through the nozzle decreases with increasing cavitation. The intensity of cavitation depends on the nozzle entrance shape. Sharp edges cause cavitation to occur early in the nozzle, followed by an inclined shape, and then the curved entrance. The dissipative energy in the cavitation and bubble collapse result in an increase in the turbulent kinetic energy of the issuing liquid. This causes more liquid disintegration, leading to larger spray volume and smaller droplet size. The obtained results for spray droplet size distribution have been compared with experimental data developed by other researchers, and a good agreement has also been found.

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Section: Introductionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Prediction of the Impact of Nozzle Geometry on Spray Characteristics

et al. 2021

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“…Therefore, the mass of compressed air in the premixed chamber will increase according to the ideal gas law shown in Formula (3). At the same time, the fuel under the current pressures (0.7 MPa-1.0 MPa) can be regarded as an incompressible fluid [34]. The pressure difference between the inside and outside of the metering fuel injector is always 0.1 MPa under any fuel injection pressure; hence, the mass of fuel injected into the premixed chamber does not vary with fuel injection pressure.…”

Section: Effect Of Fuel Injection Pressure On Spray Characteristicsmentioning

confidence: 99%

Experimental Investigation on the Effects of Injection Parameters on the Air-Assisted Diesel Spray Characteristics

Zhao

2022

International Journal of Aerospace Engineering

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The air-assisted fuel injection (AAFI) system may be installed in the spark ignition aviation piston engine for the atomization of heavy fuels. However, studies on the effects of injection parameters on the spray characteristics are insufficient, which affects the improvement of AAFI engine performance. In this study, air-assisted diesel spray characteristics are investigated experimentally using a high-speed backlit imaging technique. The effects of main air-assisted injection control parameters such as fuel injection pressure, fuel temperature, and fuel injection duration on the spray characteristics are examined. The results show that spray shape changes from “spindle” to “cone” with an increase in fuel injection pressure. As the fuel injection pressure increases to 1.0 MPa, both the spray penetration and spray width increase significantly. “Protrusions” appear on the spray edge at high fuel temperatures. When the fuel temperature drops to 268 K, the spray penetration and spray width increase slightly. The spray shrinks significantly in both the axial and radial directions with an increase in fuel injection duration. Key parameters that directly affect air-assisted spray characteristics include the difference between the fuel-air mixture injection pressure and the ambient pressure, the density of fuel-air mixture in the air-assisted injector premixed chamber, and the kinetic energy density of the fuel. The former two parameters affect the spray penetration while the latter affects the spray width. The study is beneficial for the design of AAFI engines.

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“…The modeling of flow ejectors under sonic flow conditions was considered in Reference [17][18][19][20][21]. Some of the recent papers simulating compressible flow conditions at high Mach numbers inside nozzles are Reference [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…They observed supersonic flow was impossible to set in nanoscales once Knudsen number exceeded a given value. Zhao et al [24] numerically studied the fuel flow in a nozzle considering the fuel compressibility. They used the RANS method with a Realizable k − turbulent model and they investigated the effect of injection pressure on the fuel flow under fuel compressibility conditions.…”

Section: Introductionmentioning

confidence: 99%

Discharge Coefficients of a Heavy Suspension Nozzle

et al. 2021

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The suspensions used in heavy vehicles often consist of several oil and two gas chambers. In order to perform an analytical study of the mass flow transferred between two gas chambers separated by a nozzle, and when considering the gas as compressible and real, it is usually needed to determine the discharge coefficient of the nozzle. The nozzle configuration analyzed in the present study consists of a T shape, and it is used to separate two nitrogen chambers employed in heavy vehicle suspensions. In the present study, under compressible dynamic real flow conditions and at operating pressures, discharge coefficients were determined based on experimental data. A test rig was constructed for this purpose, and air was used as working fluid. The study clarifies that discharge coefficients for the T shape nozzle studied not only depend on the pressure gradient between chambers but also on the flow direction. Computational Fluid Dynamic (CFD) simulations, using air as working fluid and when flowing in both nozzle directions, were undertaken, as well, and the fluid was considered as compressible and ideal. The CFD results deeply helped in understanding why the dynamic discharge coefficients were dependent on both the pressure ratio and flow direction, clarifying at which nozzle location, and for how long, chocked flow was to be expected. Experimentally-based results were compared with the CFD ones, validating both the experimental procedure and numerical methodologies presented. The information gathered in the present study is aimed to be used to mathematically characterize the dynamic performance of a real suspension.

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Numerical investigation of gas/liquid two-phase flow in nozzle holes considering the fuel compressibility

Cited by 21 publications

References 25 publications

Prediction of the Impact of Nozzle Geometry on Spray Characteristics

Prediction of the Impact of Nozzle Geometry on Spray Characteristics

Experimental Investigation on the Effects of Injection Parameters on the Air-Assisted Diesel Spray Characteristics

Discharge Coefficients of a Heavy Suspension Nozzle

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