空气辅助直喷汽油机缸内喷雾特性的试验

摘要

Spray characteristics of a direct-injection gasoline engine were studied using a constant volume bomb and an optical engine. Numerical simulation of airflow in-cylinder was made using CFD software. The effect of fuel injection timing and engine speed on spray characteristics of an air-assisted injector was analyzed. Spray is deflected by the influence of airflow. With delaying injection timing, the impact of airflow on spray is weakening, and deflection of spray angle is decreased and spray penetration distance is increased. Spray angle, semi-cone angle of spray and deflection of spray angle are decreased with decrease of engine speed with no significant variation in spray penetration distance.%为了解直喷汽油机缸内气流运动对喷雾特性的影响,利用定容弹及缸筒全透明式光学发动机进行了相关试验,并利用三维计算流体力学软件模拟了缸内的气流运动情况,分析了缸内气流运动、燃油喷射时刻及发动机转速等对空气辅助直喷喷嘴喷雾特性的影响.结果表明:进气气流对喷雾场有明显的吹偏作用,其作用通过引入喷雾半锥角及喷雾锥角偏移度的概念来反映；随着燃油喷射时刻推迟,进气气流对喷雾场的吹偏作用逐渐减弱,喷雾锥角偏移度随之减小,而喷雾的贯穿距离不断增大；进气气流的流速随着发动机转速的下降而降低,其对喷雾场的影响也随之减弱,喷雾锥角、喷雾半锥角及喷雾锥角偏移度均随之减小,但喷雾贯穿距离的变化并不显著.