管内高温介质流动入口段的辐射与对流耦合换热数值模拟

Numerical Simulation of the Coupled Radiation and Convection Heat Transfer of a High Temperature Developing Tube Flow

将求解辐射传递方程的离散坐标法与求解对流换热的控制容积法相结合 ,数值模拟了高温下圆管流动入口段参与性介质的辐射与对流耦合换热。考察了介质光学厚度及管壁温度对温度分布、壁面热流密度及局部努谢尔数分布的影响。结果表明 ,高温下介质辐射使介质的温度分布和对流换热状况发生较大改变 。

The coupled radiation and convection heat transfer of a high temperature participating medium in a tube is investigated by numerical simulation.The medium with constant properties is gray and flows in a developing laminar status.The conservation equations governing the convection heat transfer are discretized by the control volume method (CVM) and solved by the SIMPLEC algorithm.The radiation transfer in medium is solved by the discrete ordinate method (DOM) and its contribution to the coupled heat transfer is dealt with as the source term in the energy equation.With different optical thickness of the medium and different tube wall temperatures,the numerical results of the temperature distribution in medium,the local radiation and convection heat fluxes at wall as well as the corresponding local Nusselt numbers are presented and discussed.The reliability of the numerical results is validated by comparing with the previous investigation and by analyzing the influence of discrete grid number.The results and analysis show that the thermal radiation of high temperature medium plays an important role in the coupled heat transfer of a developing laminar flow in the tube.It has a significant effect on the temperature distribution and influences the convection heat transfer.In addition,the tube wall temperature also influences the actions of radiation and convection in the coupled heat transfer.