柴油机缸内辐射换热三维数值模拟

Study of the 3D numerical simulation of the in-cylinder radiation heat transfer of diesel engines

为了在自主开发的通用流体力学数值模拟软件GTEA上进行柴油机缸内辐射换热三维数值模拟,假设柴油机缸内气体为漫灰介质,基于非结构有限体积法(UFVM),研究了空间的非散射性辐射问题以及辐射换热三维数值计算方法。对六面体、圆柱体进行辐射换热数值方法验证,分析了不同的网格离散和立体角离散对计算结果的影响,并用此方法研究了TBD620型柴油机ω型燃烧室的辐射换热。结果表明:数值结果与精确解和文献中方法的结果吻合较好;当网格离散和立体角离散满足一定的对应关系时,才能得到更精确的计算结果;燃烧室中工质的吸收系数和温度对缸壁的热流量有一定的影响。

The three-dimensional numerical simulation of the radiation heat transfer of the diesel engine in-cylinder was performed with the general fluid flow numerical simulation solver-GTEA, which was developed independently by us. The gas used in the diesel engine cylinder was assumed to be grey medium. In this study, a three-dimensional numerical method is proposed for the spatial non-scattering radiation problem, which is based on the unstructured finite volume method （UFVM）. For its validation, a hexahedral enclosure and a cylinder enclosure were presented. The influence of different discrete meshes and solid angles on the computational results was investigated. Then, the radiation heat transfer in the combustor of the TBD620 diesel engines was studied with the present numerical method. It was found that all the results obtained by the presented FVM approach match exactly with the solutions and results of the literature. For getting more accurate results, discrete meshes and solid angles should satisfy certain relationships. The absorption coefficient and temperatures of the medium have certain effects on the radiation heat flux of the wall of the combustion chamber.