高温介质短管耦合换热中的热流分布与辐射作用

通过数值模拟短管内常物性高温介质的辐射与对流耦合换热，研究了壁面热流及介质内的热流分布特征，考察了介质辐射作用对热流分布的影响，管内流动为层流正在发展流，介质为吸收发射性灰介质，换热与流动同时发展，采用离散坐标法求解圆柱坐标系下的辐射传递方程，以获得辐射换热项，并将该项作为耦合换热能量方程的源项处理，采用控制容积法离散能量方程和N－S方程，并用SIMPLEC算法进行失代求解，结果表明，高温介质辐射不仅对壁面热流和局面努谢尔数分布有重要影响，而且使介质内径向热流分布发生较大改变。

Heat Flux Distributions and Radiation Effects During Coupled Heat Transfer in High Temperature Medium Inside Short Tubes

The heat flux distributions on tube surface and inside medium were investigated by numerically simulating the coupled radiation and convection heat transfer in a constant property high temperature medium flowing inside short tubes, and the radiation effect of medium was analyzed. The thermal state developed simultaneously with the developing laminar flow. The medium was an absorbing-emitting gray medium and a constant wall temperature was maintained. The discrete ordinate method (DOM) was employed to slove the radiative transfer equation in a nonlinear integro-differential form to obtain the radiative heat transfer term, which was taken as a source term in the energy equation governing the coupled heat transfer. The energy equation and the N-S equations were discretized by the control volume method (CVM) and solved by the SIMPLEC algorithm. The results of computation show that the radiation of medium at high temperature has significant influences not only on the heat flux distributions over the wall surface and the local Nusselt number, but also on the radial heat flux distributions in medium.