柴油机缸内火焰辐射传热新模型

New Model for Computing Flame Radiation Heat Transfer in Cylinder of Diesel Engine

:柴油机缸内的火焰辐射受诸多因素的影响 ,用理论分析法来确定它是相当困难的 ,由于柴油机缸内火焰辐射特性依赖于缸内的燃烧过程 ,而燃烧过程中的实际热力状态又可用示功图来分析 ,因此借助于火焰辐射与缸内热力参数之间的这种间接关系 ,建立了一种计算柴油机缸内火焰辐射传热的新模型 ,利用该模型对一台直喷柴油机缸内火焰辐射热流量随曲轴转角的变化情况进行了计算 ,将计算结果与实测结果进行了比较 ,表明该模型能较好预测缸内火焰辐射传热量。

It is very difficult to analyze flame radiation in the cylinder of a diesel engine by theoretical method since flame radiation is a function of many parameters,such as the combustion process,the geometrical description of the chamber,the soot formation and oxidation processes,the soot radiant temperature and soot absorption coefficient.The radiant property of the flame in a cylinder is dependent on the combustion process.But the thermodynamic state of real engine cycles can be analyzed from the pressure volume diagrams in the cylinder.Thus a new thermodynamic computational model is set up for the flame radiation in the cylinder of a diesel engine based on the indirect relationship between the flame radiation and the pressure volume diagram of the combustion process in this paper.The flame radiant heat flux in the cylinder of a DI diesel engine is calculated with the variation of crank angle by this model.Compared with measured values,the result of the computational values shows the model is available to represent the effects of flame radiation.