垂直矩形窄缝流道中混合对流换热的数值模拟

直接使用N－S方程，采用将重力项化为与温度和差压有关函数的处理方法，对垂直矩形窄缝流道中定热流密度下混合单相层流对流换热进行了数值模拟，发现了在整个流道靠近加热壁面区域存在强烈的“烟囱效应”，在层流流动时，由于该效应的存在，使近壁区域的工质扰动加强，从而提高局部对流换热系数，但将造成整个加热壁面换热系数分布不均匀，故该种对流方式只能用于较低热流密度的传热，若壁面的热流密度过高，将对整个流道的安全性造成很大威胁，所建立的浮力影响模型可以预测混合对流时的传热，经过正能用于计算湍流混合对流换热。

Numerical Simulation of Laminar Mixed Convection Heat Transfer in Vertical Narrow Rrectangular Channels

Using N-S function, and transforming the gravity item to temperature and differential pressure related items, the authors simulate the mixed convection heat transfer in vertical narrow rectangular channels. The results reveal that intense chimney effect exists in cross-section of the whole field and nearby the wall of the channel, When flow is laminar, the velocity of main flow will be decreased, disturbing nearby the heating wall is strengthened, and the convection heat transfer of vertical narrow rectangular channel is enhanced. It also can destroy the uniformity of the heat transfer coefficient distribution. Considering the reliability of equipment, this kind of convection pattern only can be used in low heat flux. The buoyancy-influencing model putted forward can predict mixed convection heat transfer, and also can be used to simulate the turbulent mixed-convection heat transfer problem.