不同喷油压力RP-3航空煤油,柴油碰壁喷雾着火和燃烧特性的对比研究

The ignition and combustion characteristics of wall-impinged kerosene(RP-3) and diesel spray were comparatively investigated under the condition of a fixed injection mass and different injection pressures and based on calibrated fuel injection quantity data and corresponding control parameters. Adopting a common rail nozzle with single-hole of 0.22 mm, the experiments were conducted in a constant volume combustion vessel to simulate diesel engine condition. Flame images were captured using a high-speed camera, and then the behaviors of ignition and combustion were processed. The variation laws of ignition position, ignition delay time, combustion duration, flame area(AF) and spatially integrated natural luminosity(SINL) of both wall-impinged fuel sprays were determined by analyzing the flame images. The results show that at low injection pressures, the ignition positions of both fuels are in the region that is far from the wall surface. At high injection pressures, the ignition positions of both sprays are on the wall surface, and are pushed farther away from the injector center-line with the increase of the injection pressures. The ignition positions of the kerosene spray are farther away from the injector center-line than those of the diesel spray. The ignition delay of the wall-impinged kerosene flames shortens first and then prolongs with the increase in the injection pressure, and that of the diesel flames reduces with the increased injection pressure. The kerosene RP-3 spray has a shorter ignition delay than the diesel spray. The combustion durations of both sprays are shortened with the increased injection pressures, but that of the kerosene RP-3 spray is shorter. Increasing the injection pressures enhances the variation rates of AF and SINL of both sprays, but the maximum values of AF and SINL and the time to reach them decreases. The kerosene RP-3 spray has higher variation rates of AF and SINL, greater values of the maximum AF and SINL, and shorter time to reach the maximum AF and SINL compared to the diesel spray.