Effect of split injection ratio on combustion process of diesel spray into two-dimensional piston cavity

Abstract

The purpose of this paper is to further understand the effect of split injection ratio on the diesel impinging spray combustion characteristics. Diesel combustion formed in the two dimensional piston cavity was studied in a high ambient pressure and high ambient temperature chamber. The injection pressure was 160 MPa and the diameter of single nozzle hole was 0.111 mm. Three split injection ratios were used: 25:75, 50:50 and 75:25. The KL factor and temperature distributions of the three injection strategies were analyzed and discussed. On this basis, the influence of the split injection ratio on the integrated KL factor and the flame temperature is discussed. The experimental results show that extending the splitting interval and decreasing the 2nd/1st ratio are beneficial to avoid the “catch-up” effect and reduce soot. In the absence of a “catch-up” effect, the domain process of soot formation and oxidation zones can be divided into six phases. However, the split injection influence on the flame is completed simultaneously. Due to the pre-injection, ignition is easier during the main injection. The relationship between the spatial KL factor and temperature is also discussed.