涡轮叶片内部沿周边分布的竹节孔换热特性研究

根据发动机涡轮叶片内部沿周边分布的竹节孔冷却通道结构建立了简化的传热分析模型。首先通过无量纲分析得到了竹节孔的平均努塞尔数不仅与雷诺数和普朗特数有关，还与“竹节”形状、通道外壁形状以及流体和固体的导热系数比等参数有关。然后，对雷诺数和冷却通道几何参数对竹节孔平均努塞尔数的影响进行了数值模拟研究，计算并对比了上述参数对平均努塞尔数的影响规律，结果表明：（1）“竹节”结构使平均努塞尔数显著增大，而通道外壁形状主要影响了局部热流密度和局部努塞尔数的分布情况；（2）随着通道内的雷诺数和“竹节”的节高/孔径比的增加，平均努塞尔数单调增大。但以增大节高/孔径比的途径来提高平均努塞尔数时，阻力系数迅速增大；（3）可通过增大雷诺数和优化节距/节高比来提高竹节孔的平均努塞尔数，计算表明最佳节距/节高比约为10。

A study of heat transfer of inner turbulated cooling holes of turbine balde

A simplified heat transfer analysis model is extracted from the inner turbulated cooling holes, which is placed in close proximity to the periphery of the air foil of a turbine blade. The turbulators of the holes are ring ribs, with rectangular cross section. By dimensional analysis, it is shown that the Nusselt number of the cooling holes is affected not only by Reynolds and Prandtl numbers, but also by the geometry of the turbulator, by the distance between the hole and the outer surface of the blade, and by the ratio of fluid conductivity to solid conductivity. A detailed numerical study of the effect of Reynolds number and geometry parameters of the cooling holes on its Nusselt number shows that: (1) the ring ribs increase the average Nusselt number, while the distance between the hole and the outer surface of the blade affects the local heat flux and Nusselt number dis-tributing;(2)the Nusselt number monotonously increase with the increase of ratio of rib height to holes diameter, e/d, but it also lead to rapid increase of friction coefficient; (3) by increasing Reynolds number and optimizing the ratio of rib pitch to rib height, p/e, Nusselt number of the cooling hole can be increased, the optimized value of p/e is about 10.