直喷汽油机附壁油膜特性试验研究

运用激光诱导荧光法(LIF)定量分析了缸内直喷汽油机单孔喷油器喷雾撞壁的二维油膜特性。研究发现:燃油在壁面上向油膜铺展的方向聚集,并在边缘形成较厚的油膜。高喷射压力有助于形成质量较小且厚度较薄的油膜,同时减小喷射脉宽能进一步降低燃油附壁率。增加撞壁距离能同时减小油膜质量和油膜面积,然而油膜的平均厚度并未减小,对油膜蒸发并没有明显的促进作用。将喷射角度从15°增加到45°能够显著减少油膜质量和平均厚度。

Experimental Study on Oil Film Characteristics of Direct Injection Gasoline Engine Spray Wall Impingements

The two-dimensional oil film characteristics of the single-hole injector spray wall impingements in a direct injection gasoline engine were quantitatively analyzed by the laser induced fluorescence method. Results show that the fuel accumulates on the wall in the direction of oil film expansion and forms a thicker oil film on the edge. High injection pressure helps to form an oil film with a lower mass and a thinner thickness, while reducing the jet pulse width can further reduce the fuel adherence rate. Increasing the wall impingement distance can simultaneously reduce the oil film quality and the oil film area, but can not reduce the average thickness of the oil film, so there is no obvious promotion effect on the oil film evaporation. Increasing the spray angle from 15° to 45° can significantly reduce the oil film quality and average thickness.