柴油机高压喷雾碰壁前后粒子速度的LDA试验研究

LDA Measurement of Droplet Velocities in a High Injection Pressure Diesel Fuel Spray

利用 3光束二维氩离子激光多普勒测速仪对柴油机高压喷雾碰壁前和碰壁后的粒子速度进行了试验研究。结果表明 :喷雾中液体粒子速度分布范围很宽 ,在距离喷嘴 70 mm处 ,粒子速度仍可达 10 0m/s左右 ,且沿径向分布平坦 ,与气体射流速度的分布不同。在喷雾可见边界之外测量到有高速粒子存在。喷雾碰壁后 ,反弹粒子速度的统计值大大衰减 ,且主要为沿壁面爬行。滴群的运动形态类似于碰壁后的气体射流而不同于碰壁反弹的固体颗粒。

A study of the droplet velocities in high injection pressure diesel fuel sprays using 3-beam 2-conponent Ar-ion LDA is presented.The experimental results show that the droplet velocity frequency bandwidth at high injection pressure is dispersed.At 70 mm point away from the nozzle,the highest droplet velocity is still about 100 m/s,and the velocity distribution of the droplets in a spray along the radial direction is smooth,which is different from that of a gaseous jet.However,outside of the visible spray boundary droplets with high velocity are still detectable.After the spray impinging on the wall,the droplet velcocities will obviously become slow and its direction will be almost parallel with the wall surface.The droplet movement is similar to gaseous jet after the spray impinging on the wall not alike solids reflection.