同速对转涡轮盘腔内流动和换热特性

Characteristicsof Flow and Heat Transfer in Counter Rotating Turbine Disc Cavity with Same Rotation Speed

为研究对转盘旋转速度对盘腔内换热效果的影响,应用RNG k-ε湍流模型对中心进气、径向出流的同速对转涡轮盘腔内的流动和换热特性进行了数值模拟。揭示了盘腔内气体的流动结构、两盘壁面边界层内的径向速度、换热效率以及壁面温度分布特征,并进一步探究了转盘转速对上述流动和换热特征的影响规律。结果表明:对转盘腔内存在两个反向的回流涡胞,这两个涡胞的相对大小以及相遇的滞止点位置取决于进气惯性力和旋转力的相对大小;转盘近壁面流体径向流动速度与盘壁面的对流传热系数呈正相关变化;对于上游盘,低转速范围时转速对壁面换热影响取决于旋转径向力和进气惯性力对上游盘近壁面流体流动驱动作用的相对大小,高转速范围内增大转速,上游盘壁面传热系数增大,壁面温度降低;对于下游盘,壁面低半径区域的对流传热系数随转速增大而减小,而高半径区域的对流传热系数随转速增大而增大。

The flow and heat transfer characteristics in the counter-rotating turbine disk cavity with central axial air inflow were numerically simulated using the RNG k-εturbulence model for exploring the effect of rotation rate on the wall heat transfer.The characteristics of the flow structure in the disk cavity,the radial velocity,the heat transfer efficiency and the wall temperature distribution in the boundary layer of the two walls were discovered,and the influences of the rotation speed on these characteristics were further explored.The results show that there are two counter recirculation vortices in counter-rotating disc cavity,and the relative size of the two vortices and the radial position of the stagnation point depend on the relative magnitude of the air intake inertial force and the rotation force.The radial velocity on the near wall plays a major role in the wall heat transfer efficiency.For the upstream disk,the effects of the rotation speed in the low speed range on the wall heat transfer depend on the relative driving role of the air intake inertial force and the radial rotation force on the fluid flow near the upstream disk wall,while the heat transfer coefficient increases and the wall temperature decreases with the increase of the rotation speed in the high speed range.For the downstream disk wall,the convective heat transfer coefficient decreases in the lower radius wall region while increases in the high radius wall region with the increase of the rotation speed.