柴油机缸内辐射换热的多维数值模拟研究

对柴油机来说，辐射换热极为重要，在缸内总传热量中占有非常大的比重，直接关系到发动机热效率及因传热引起的各种热负荷、热强度问题，同时，辐射换热对燃烧系统的研究也十分重要，辐射热流量会深刻影响内燃机的燃烧性能，对发动机的各种燃烧产物的形成产生至关重要的影响。为此，利用离散传递法实现柴油机缸内辐射换热的多维数值模拟，通过多维模拟计算同时考察燃烧室部件表面发射率及喷雾提前角对柴油机缸内辐射换热的影响。结果表明：活塞的辐射热流量峰值高于缸盖的辐射热流；缸盖的辐射热流量的最大值并不在中心位置处，而是随时间变化；随着壁面辐射率的增加，缸内向燃烧室部件辐射换热量逐渐增大；喷雾提前角直接影响所有燃烧室部件表面的辐射热流密度。

Study on Multi-dimensional Numerical Simulation of In-cylinder Radiation Heat Transfer of Diesel Engine

Radiation heat transfer is extremely important for diesel engine and occupies very high ratio in total heat transfer capacity of in-cylinder. It is directly related to the diesel engine heat efficiency and all kinds of heat load and heat intensity caused by heat transfer. At the same time, the study on radiation heat transfer on combustion system is also important, for the combustion performance of internal combustion engine and formation of all combustion products will be observably effected. Hence, the multi-dimensional transient numerical simulation of in-cylinder radiation heat transfer is performed by using discrete transfer radiation method (DTRM), and the effect of surface emissivity and fuel injection advance angle on in-cylinder radiation heat transfer is investigated. The results show that the maximal radiative heat flux of piston surface is larger than that of head surface; the maximal radiative heat flux of head surface is not at the central position but changes with time. The radiative heat flux of wall surfaces is enhanced with the increase of emissivity of wall surfaces; the radiative heat flux of all combustion chamber components is directly affected by the advance angle of fuel injection.