Impact and Sensitivity of the Curvature of Turbine Cascades on the Film Cooling Effectiveness

在本研究项目中，将从气膜冷却效果的角度来考察轮毂和机壳的曲率对二次流的影响。对轮毂半径的不同参数和泄漏流进行了研究。曲率参数的影响定义为弦长与轮毂半径的比率。计算结果为估算曲率对气膜冷却效率的敏感性提供了可能。这种关于参数对曲率影响的研究直到今天才被完成。灵敏度定义为σ=dη_ad/d RN。σ将在当地确定，即对于所有点，通过应用S/RN=0.2和0.3的相应σ结果的中心差值报价来确定CFD。此外，还确定了积分灵敏度。因此，敏感度在轮毂和机壳表面上取平均值。本课题采用数值计算和实验相结合的方法，但由于成本较低，实验研究仅限于某一透平叶栅。实验结果用于数值模型的验证。这些试验是对NASA节能发动机计划(E3)的圆柱形导叶进行的，该计划已经对其线性叶栅进行了研究。

In this research project the influence of the curvature of the hub and casing on the secondary flow is to be examined with regard to the film cooling effectiveness. The investigations are performed for differnet parameters of the hub radius and for leakage flow. The impact of the curvature parameter is defined as the ratio of the chord length and the hub radius. The results make it possible to estimate the sensitivity of the curvature on the film cooling effectiveness. Such an investigation of the impact of the curvature by parameters have not been done until today. The sensitivity is defined as σ = d η_ad/d RN. σ is to be determined locally, i.e. for all points σ is determined by applying a central difference quotation of the corresponding CFD results of S/RN = 0.2 and 0.3. Additionally, the integral sensitivity is determined. Therefore, the sensitivity is averaged over the hub and casing surface. The project is performed by numerical and experimental methods, whereas the experimental investigations are restricted on one turbine cascade due to reducing the costs. The experimental results are used for the validation of the numerical model. The tests are performed for the cylindrical guide vanes of the NASA Energy Efficient Engine Program (E3) which was already investigated for its linear cascade.