旋转状态下气膜冷却特性的数值研究

 通过对带有气膜孔倾斜角度为30°，60°和90°圆柱形交错孔排的涡轮叶片模型进行数值模拟，得到了不同平均吹风比、雷诺数和旋转数情况下前缘面侧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在前缘面侧向高半径处发生偏转，导致壁面冷却效率降低；雷诺数的增大会降低壁面上的气膜冷却效率，高吹风比则不利于紧贴气膜孔下游区域的冷却;各气膜孔的流量系数随着平均吹风比的增大而增大，随旋转数的提高而减小；受哥氏力作用的影响，相同工况下后缘面侧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 of Film Cooling Characteristics on a Rotating Turbine Blade Model

Computations are performed to simulate the flow and heat transfer characteristics of film-cooled rotating turbine blade models under different operating conditions. The chosen blade is a mid span segment of a typical turbine rotor with two rows containing 14 staggered injection holes on both leading surface and trailing surface. The inclination angles to the leading and trailing surfaces are φ=30°, 60° and 90°, respectively. Detailed distributions of adiabatic film cooling effectiveness, Nusselt number and discharge coefficient on the leading and trailing surfaces are presented at various values of averaged blowing ratio,mainstream Reynolds number,and rotation number.Results show that the coolant is stroogly influenced by the centrifugal force and Coriolis force to deflect toward the high-radius locations beside the leading surface, and this will lead to lower adiabatic effectiveness.The high values of blowing ratio are not suitable for the thermal protection near the exit of cooling holes,and the enhancement of Reynolds number can reduce the adiabatic effectiveness slightly.For discharge coefficient distributions,all the coefficients decrease with the increase of rotation number and increase with the augmentation of blowing ratio.Moreover,the discharge coefficient values beside the trailing surface are much higher than that beside the leading surface under the same operating conditions.