Numerical simulation of the effects of nozzle geometry on the in-nozzle flow-characteristics of flash boiling sprays

doi:10.3969/j.issn.1674-8484.2024.03.009

Abstract

Abstract:

This paper investigated the influence of nozzle geometry on the in-nozzle flow and phase-change process of flash boiling sprays in the direct-injection gasoline-engine cars. A one-dimensional two-phase-flow model was developed based on the thermal non-equilibrium assumption to analyze the in-nozzle flow characteristics of the flash boing spray with different nozzle lengths, different diameters, different rounding angles at the inlet, and different taper angles. The model’s results were verified through the accuracy comparison with the previous experimental results by the authors' team. The results show that the longer the nozzle channel length, the smaller orifice diameter, and the more intense of the phase transition in nozzles, while the round corners at the nozzle entrance reduces the vapor generated inside nozzles. The convergent nozzle has a smaller pressure drop and the generation of vapor phase inside the nozzle is reduced accordingly, while the divergent nozzle increases the vapor generation rate. The different nozzle geometries change the pressure distribution and the velocity distribution in the nozzle. The pressure distribution governs the bubble growth rate, while the velocity distribution affects the bubble growth time, both of which ultimately affect the phase change characteristics within the nozzle.

Key words: automotive power, gasoline direct-injection engines, flash boiling spray, thermal non-equilibrium, in-nozzle flow, two-phase flow, numerical simulations

CLC Number:

U464.136+.1

YIN Peng, XU Min. Numerical simulation of the effects of nozzle geometry on the in-nozzle flow-characteristics of flash boiling sprays[J]. Journal of Automotive Safety and Energy, 2024, 15(3): 360-367.

Figures/Tables 9

References 35

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参数	液相	气相
液相修正压强，p_∞ / MPa	181.96	0.00
定容比热，c_v / [kJ·(kg·K)^-1]	1.902	1.477
比热比，γ	1.368	1.074
修正比体积，b / (cm³·g^-1)	0.439	0.00
修正焓， q / (kJ·kg^-1)	-806.99	-132.82
修正熵， q' / [kJ·(kg·K)^-1]	0.00	-5.064

参数	液相	气相
液相修正压强，p_∞ / MPa	181.96	0.00
定容比热，c_v / [kJ·(kg·K)^-1]	1.902	1.477
比热比，γ	1.368	1.074
修正比体积，b / (cm³·g^-1)	0.439	0.00
修正焓， q / (kJ·kg^-1)	-806.99	-132.82
修正熵， q' / [kJ·(kg·K)^-1]	0.00	-5.064

喷射压力	0.5、2.0 MPa
环境压力	101、120 kPa
燃油温度	41、65、71 ℃
喷嘴长度	10、14、25 mm
流道直径	0.8、1.0、1.5、2.0 mm
喉口圆角半径	0.0、6.0 mm
锥度角	直线性、扩张型、收缩型

喷射压力	0.5、2.0 MPa
环境压力	101、120 kPa
燃油温度	41、65、71 ℃
喷嘴长度	10、14、25 mm
流道直径	0.8、1.0、1.5、2.0 mm
喉口圆角半径	0.0、6.0 mm
锥度角	直线性、扩张型、收缩型