组分比例对闪沸射流相变诱导激波宽度的影响
Effect of Component Proportions on Phase Change Induced Shock Wave Width in Flash Boiling Jets
许鹿冰 1徐海丰 1李雁飞 1马骁 1帅石金1
作者信息
- 1. 清华大学智能绿色车辆与交通全国重点实验室,北京 100084
- 折叠
摘要
闪沸射流发生欠膨胀并诱发激波间相互作用是汽油直喷喷油器的喷雾坍塌的主要原因,但液体组分比例对闪沸诱导激波的影响特性和机制尚不清楚.利用纹影法,在定容弹中研究了闪沸条件下乙醇/正己烷混合比例对激波宽度的影响,喷射温度(Tinj)从30℃到150℃,环境压力(Pamb)从10 kPa到200 kPa.结果表明,提升喷射温度和减小环境压力,均会增加激波宽度.在相同喷射温度和环境压力下,乙醇含量增加会导致激波宽度呈现先增后减趋势,其主要是因为相变吉布斯能差(△G)随乙醇含量增加呈现类似规律;通过进一步量化△G和激波宽度的关系,发现激波宽度和△G·P-0.5amb强线性相关,表明闪沸射流的激波宽度受到相变与环境阻力的控制.
Abstract
The under-expansion of flash boiling jets and the ensuing shock interaction are the main reasons for spray collapse of the gasoline direct injection(GDI)engine,but lack of investigations on the effects of component proportions on shock waves in flash boiling jets.High-speed microscopic Schlieren photography was used to investigate the influence of varying ethanol/n-hexane blending ratios on shock width.Tests were carried out in a constant volume vessel with ambient pressures(Pamb)from 10 to 200 kPa,and fuel injection temperatures(Tinj)from 30 to 150℃.For all studied liquids,increasing Tinj and/or decreasing Pamb causes an increase in shock width.For given Tinj and Pamb,shock width varies non-monotonically with increasing ethanol blending ratio,mainly caused by the non-monotonical change in △G(Gibbs energy difference during phase change)of the fluids.Further analysis to corelate shock width with △G showed that shock width has a strong linear correlation with △G·P-0.5amb,indicating that phase change and ambient resistance contribute to the radial expansion of shock waves in flash boiling jets.
关键词
闪沸/欠膨胀射流/激波/双组分液体/组分比例Key words
flash boiling/under-expanded jet/shock waves/two-component liquids/component proportion引用本文复制引用
出版年
2024
NETL
NSTL
万方数据