柴油机气缸内工质辐射物性参数计算模型

Modeling of Radiated Heat Transfer Parameters inside a Diesel Engine Cylinder

对 G4135型直喷式柴油机建立了一个辐射多区多维模型 ,包括缸内工质的几何空间模型、辐射温度模型 ,以及辐射发射系数、吸收系数及燃料油滴的散射系数模型。综合考虑碳烟的形成和氧化过程提出了一个新的辐射温度模型 ,代替过去仅用平均气体温度作为辐射温度的简单方法 ,并分析了在不同工况条件下 ,各区域平均吸收系数的变化趋势。结合实验数据进行了编程计算 ,计算所得的气缸内工质辐射物性参数结果及其变化趋势与实验相吻合 。

A multi zone and multi dimentional radiated heat transfer model for a G4135 diesel engine was developed based on fuel spray model. It consists of a geometrical model of combustion chamber, a radiated temperature model, an emissive and absorptive coefficients model and a fuel drop scattering coefficient model. A new radiated temperature model was defined instead of the conventional average gas temperature one through considering a combined process of soot production and oxidation. The changes of average absorptive coefficients in each working zone under various operating conditions were analyzed. The results from the model and the observed data were well coincident. The work laid the foundation of the calculation of radiated heat flux distribution in combustion chamber.