尾迹作用下叶片表面非定常传热特性的数值分析

Numerical Analysis of Heat Transfer Characteristics on Turbine Blade Surface Under the Action of Unsteady Wakes

基于非定常RANS方程,采用尺度自适应湍流模型,模拟分析了某透平级的非定常流动与传热,研究在不同尾缘冷气射流条件下上游静叶尾迹结构的变化及其对下游动叶表面传热的影响.结果表明:导叶尾缘冷气射流对动叶表面传热的作用主要来自湍动能尾迹的传播,动叶压力面后部的时均表面传热系数提升约20%,但是动叶吸力面传热的时均值基本没有受到影响;带有冷气射流的尾迹给下游带来的扰动强度与范围更大,下游叶片表面的传热幅值波动加剧,这一特征随着冷气射流的动量比与速度比的增大而增强,动量比为1时,波动幅值相较无冷气射流工况时提高1倍.

A simulation analysis was conducted on the unsteady flow and heat transfer of a gas turbine stage based on unsteady RANS equations and scale-adaptive turbulent model, so as to study the wake structure of upstream stator blade and analyze its influence on the heat transfer over downstream blade surface under different effects of trailing edge coolant ejection. Results show that the effects of trailing edge coolant ejec- tion on the heat transfer over rotor blade surface mainly come from the spreading of turbulent kinetic ener- gy wake, which increases the time-averaged Nusselt number by about 20% for the rear part of pressure surface, while its impact on suction surface can be neglected. The wake with coolant ejection enhances the intensity and scope of disturbance in downstream areas, and increases the amplitude fluctuation of down- stream blade surface heat transfer. This feature becomes more obvious with the rise of momentum ratio and velocity of coolant ejection; for the momentum ratio of 1, the fluctuation in amplitude would be twice of that without trailing edge coolant ejection.