LPG碰壁喷雾的试验及数值模拟研究

Numerical Simulation and Experimental Research of LPG Spray Wall-Impingement

基于离散液滴模型(DDM),并结合柴油机实际工作情况,建立了喷雾碰壁的数学模型。将该模型与KIVA程序耦合,对多种形态的喷雾碰壁进行了模拟计算。在压力定容室内,利用PIV高速摄影技术对液化石油气(LPG)和柴油的碰壁喷雾过程进行了试验研究。将模拟与试验结果进行了对比分析,并着重考察了碰壁角度对燃料碰壁过程的影响,获得了LPG喷雾碰壁特性的一般规律。与柴油相比,在同样条件下,LPG能在壁面上溅起较厚的液滴雾层,且溅起的液滴尺寸较小,在壁面上附着的油膜厚度较薄,说明LPG比柴油蒸发速度快,雾化质量好;随着碰壁喷雾倾斜角的增大,2种燃料在碰撞点壁面附近所产生的液滴数显著减少。

A mathematic model of spray wall-impingement was established based on discrete droplet model（DDM） considering the operating conditions of diesel engine.The model was then coupled with KIVA program and various forms of spray wall-impingement were numerically simulated.The spray wall-impingement experiments of LPG and diesel fuel were carried out in a constant volume chamber using PIV high speed camera.Simulated and experimental results were comparatively analyzed with emphasis on the influence of impinging angle on the wall-impingement characteristics of the fuel.The general characteristics of the wall-impingement of LPG were obtained.It was found that the LPG can induce more and smaller droplets and thinner liquid film on the wall than that of the diesel fuel under the same conditions,which indicates that LPG possesses faster evaporation rate and better atomization quality.With the increasing of the spray incline-angle,liquid droplets near the wall significantly decrease for both two kinds of fuel.