透平叶片顶部间隙流动特性的实验和数值研究

利用粒子图像测速技术(PIV)捕捉透平叶片顶部泄漏流特征,并以此数据验证湍流模型和用商业软件CFX12.0进行的数值模拟方法.所研究的叶片为典型的GE-E3叶片,为了展示泄漏涡的生成和发展过程,用实验数据展示了3个不同截面的速度分布.数值计算中使用了混合网格生成技术及5种湍流模型.通过与实验数据的比较发现:RNG k-ε模型计算所得的泄漏涡与实验所拍摄的真实流动能较好地吻合.此模型和计算方法同样适用于研究叶顶射流对泄漏流的影响.计算结果显示:通过叶片顶部气膜孔射流产生的阻挡效应,最多能降低6.12%的主流泄漏.

Experimental and numerical investigation on turbine blade tip leakage flow characteristics

The flow characteristics of turbine blade tip leakage were measured with a particle image velocimetry(PIV) system,and the experimental data was used to estimate the turbulence model and numerical simulation conducted with commercial software CFX12.0.The test model was a typical GE-E3 blade.To exhibit the generation and development of leakage vortex,three velocity distribution profiles obtained by the PIV system are exhibited.Hybrid mesh generation process and five turbulence models were used during the numerical simulation.Through comparison of experimental data with the simulation results,it can be seen that the vortex obtained by using RNG k-ε model was closer to that captured by PIV system.This turbulence model and numerical approach can be used to estimate the effects of blade tip injection.The numerical results indicated that with coolant injection through the film holes at the blade tip,the leakage flow rate can be reduced by 6.12% at most.