旋转状态下气膜冷却模型的数值模拟

通过对带有90°倾角圆柱形交错孔排的涡轮叶片模型进行数值模拟,得到了不同主流雷诺数、旋转数和吹风比情况下前缘面与后缘面侧的气膜冷却流动与换热特性及各气膜孔流量系数的分配规律.结果表明,冷气受到离心力与哥氏力的共同作用向高半径处发生偏转,导致壁面冷却效率降低;雷诺数的增大会削弱气膜冷却效果,高吹风比则不利于气膜孔下游区域的冷却.各气膜孔的流量系数随吹风比的增大而增大,随旋转数的提高而减小.在后缘面侧,相同工况下各气膜孔的流量系数明显高于前缘面侧对应气膜孔的值.

Numerical study for film cooling characteristics on rotating model

Computations were performed to simulate the two rows of 90° staggered holes film cooling characteristics over a rotating turbine blade model both on leading and trailing surfaces. The influences of the Reynolds number Re, rotation number Rt and the blowing ratio M on the film cooling effectiveness η and discharge coefficient C_d distributions were presented. Results show that the coolant is influenced by the centrifugal force and Coriolis force to deflect towards the high-radius locations, and this will lead to low values of η . The enhancement of Re can impair the film cooling effectiveness, and the high values of M are not suitable for the thermal protection near the exit of cooling holes. All the discharge coefficients increase with the augmentation of M , and decrease with the increase of Rt . Moreover, the C_d values beside trailing surface are much higher than that beside the leading surface under the same operating conditions.