柴油机内锥碰撞式伞状喷雾燃烧系统性能试验

Conical Spray Combustion System of Diesel Engine with Inner Conical-face Impingement Mode

为提高直喷式柴油机缸内油气的混合速率及其分布均匀度,利用从多孔油嘴喷出的油束撞击设置在喷孔出口外围的内锥导向面上,扩展成近似的伞状喷雾,喷雾的碰撞量可以通过改变喷孔和碰撞面的相对位置来调整。应用FIRE8.4对全碰和半碰喷雾及多孔自由喷雾的空间分布特性进行了模拟分析。结果表明:与自由喷雾相比,内锥碰撞式伞状喷雾具有扩散度高、周向分布均匀的特点。在单缸135型柴油机上进行的燃烧性能对比试验表明:半碰方式好于全碰方式,半碰方式时采用4孔油嘴优于6孔油嘴,适当的供油提前角有利于实现柴油机的热预混合燃烧。

When spray is iniected form multi-hole nozzle, oil bundle is impinged on the inner conical-face orientation sleeve mounted on the outside of nozzle and diffuses along the cone-shape surface, and then the conical spray is formed. The impingement quantity of spray can be adjusted by changing the relative position between nozzle hole and impingement surface. Three-dimensional CFD package AVL FIRE 8.4 is used to simulate and analyze the diffusion characteristics of full-impingement conical spray, half-impingement conical spray and multi-hole free spray. The simulated results show that： comparing with free spray, inner conical-face impingement type conical spray has the characteristics of high diffusion and homogeneous circumferential dispersion. Combustion performance test, which is carried out on 135-type single-cylinder diesel engine, shows the following conclusions： half- impingement mode is better than whole-impingement mode; for half-impingement mode, 4-hole nozzle is better than 6-hole nozzle; appropriate fuel supply advance angle is good for achieving hot premixed combustion.