横流马赫数对溢流孔附近流动及换热的影响 *

Effects of Cross-Flow Mach Number on Flow and Heat Transfer Characteristics Around Effusion Hole

关键词:  涡轮叶片  马赫数  溢流孔  冷却通道  横流比  换热系数  数值模拟

Key words:  Turbine blade  Mach number  Effusion hole  Cooling channel  Cross-flow ratio  Heat transfer coefficient  Numerical simulation

摘要:

为了研究冷气通道横流马赫数变化时溢流孔附近流动和换热情况，选取光滑冷却通道、90°溢流孔冷却通道和45°溢流孔冷却通道作为研究对象，保持入口雷诺数为8×104，在横流比分别为0.5和1的情况下，对横流马赫数为0.2和0.7时溢流孔附近流动及换热特性进行数值模拟。研究发现:在相同入口雷诺数和横流比条件下，横流马赫数由0.2增大为0.7时，溢流孔内的回流范围减小，孔内流动阻力变小，冷却通道壁面换热减弱。当横流比变化时，低横流比情况下横流马赫数对冷却通道壁面换热影响要更大。

Abstract:

Heat transfer and flow characteristics in a rectangular channel with 90° and 45° effusion hole under the cross-flow Mach number of 0.2 and 0.7 have been numerically studied. The entrance Reynolds number is 8×104 and cross-flow ratio is 0.5 and 1. A smooth channel was also investigated to get a reference for calculation. Numerical results reveal that when both the entrance Reynolds number and cross-flow ratio are constant，with an increase in cross-flow Mach number from 0.2 to 0.7，the range of inverse flow in the effusion hole is decreased and thus the flow resistance is weakened. Besides，the local heat transfer near the effusion holes is weakened with increase of the cross-flow Mach numbers. Additionally，the cross-flow Mach number，under the low cross-flow ratio，has a stronger effect on the heat transfer on cooling channel wall in comparison with the high cross-flow ratio.