Experimental study on spray characteristics of six-component diesel surrogate fuel under sub/trans/supercritical conditions with different injection pressures

Abstract

The purpose of this study is to explore the spray characteristics of six-component diesel surrogate fuel under sub/trans/supercritical conditions with different injection pressures and provide a reference for numerical simulation. The experiments were conducted in a constant volume chamber. The liquid- and vapor-phase spray images were captured by backlight illumination and schlieren imaging technology, respectively. Some macroscopic parameters were obtained and analyzed, such as spray structure, spray penetration, liquid-core index, spray cone angle, gas entrainment mass, spray perimeter, spray area, and spray irregularity. Results show that the variation law of the liquid-phase penetration shows opposite trend with injection pressure depending on ambient temperature. The liquid-phase spray is more stable with a smoother surface under supercritical conditions. The spray cone angle is mainly related to ambient temperature and pressure. The gas entrainment mass increases with decreasing ambient temperature or increasing ambient pressure. When the ambient pressure is twice fuel’s critical pressure, the liquid-phase spray irregularity is smaller, but an increase in injection pressure can further increase the spray irregularity. When the ambient temperature is higher than the critical temperature, increasing the injection pressure or ambient pressure is conducive to increasing the ratio of pure vapor-phase spray and improving the spray characteristics.