柴油机喷雾两相流蒸发混合的数学模型研究

提出了预测直喷式柴油机燃油喷雾蒸发和混合过程的数学模型.基于紊流射流的积分方法,在计及喷雾平均油滴直径和油滴分布指数随蒸发过程而变化的情况下,通过气相射流子模型和油滴蒸发子模型的有机结合,使柴油机喷雾两相流的计算大为简化.与复杂的密集喷雾模型相比,本模型的计算工作量很小,而两者的计算结果却符合较好.

A Two-Phase Flow Model for the Prediction of the Evaporation Spray Mixing Process in Diesel Engines

A simplified mathematical model for predicting the mixture forming and evaporating process of the fuel spray in the D. I. type diesel engine is developed. In order to improve computational efficiency, the conservation equations for mass and momentum of the fuel spray are given in integral form using similarity profiles for instantaneous concentration, velocity and temperature within the spray. It is assumed that the radial distribution of the fuel droplet in the normalized size range follows a well established concentration profile. The effects of the initial mean droplet diameter and the droplet size distribution on the subsequent evaporation history and their variation with evaporation time have been taken into account. The model can be used to calculate the fuel spray characteristics, fuel evaporation history and preparation rate of the flammable fuel-air mixture as well as to predict the effects of some operating variables on the characteristics of diesel spray. The model is characterized by simple and quick algorithm. Predicted results by this model have been compared and found to be in good agreement with existing analytical and experimental data.