关键词: 闪沸喷雾, 非闪沸喷雾, 喷雾特性, 喷雾坍塌, 可视化技术

Abstract: The rapid boiling that occurs when high-temperature fuel is injected into a low-pressure environment is called flash boiling, reasonable use of flash boiling phenomenon can effectively improve the atomization effect of fuel spray and improve engine efficiency. The research on the flash boiling phenomenon can be traced back to more than 60 years ago. With the development of the research on the flash boiling spray, the focus of the spray-related research has gradually shifted to the spray collapse. The related theories of flash boiling spray are summarized in this review, and some visualization techniques commonly used in the observation of flash boiling spray are briefly introduced. The influence of different fuel characteristics on the flash-boiling spray is illustrated by comparing different fuel characteristics. The characteristics of flash boiling spray of multi-component fuel are summarized. The superheat index which can be used to measure the flash boiling spray of multi-component fuel are introduced. The collapse mechanism of non-flash boiling spray and flash boiling spray and the influencing factors of spray collapse are studied by comparing the research status of non-flash boiling spray and flash boiling spray. It is generally considered that the collapse mechanism of non-flash-boiling spray is jet-induced collapse, and flash-boiling spray seriously affects the experimental observation because of too many droplets. Therefore, the understanding of the collapse mechanism of the flash boiling spray is numerous but not certain. In addition, according to the above summary, several feasible research directions are put forward for the spray research: effect of different fuel properties on flash boiling spray, study of parameters to measure the degree of superheat of multi-component fuels, the study on the collapse mechanism of the flash-boiling spray and the study on the suppression of the collapse of the flash-boiling spray.

Key words: flash boiling spray, non-flash boiling spray, spray characteristics, spray collapse, visualization technology