扫频式射流对涡轮叶栅间隙泄漏流动影响的数值研究

Numerical Study for Effects of Sweeping Jets on Tip Clearance Flow in a Turbine Cascade

关键词:  流动控制  间隙泄漏流  扫频式射流器  非定常流动  涡轮平面叶栅

Key words:  Flow control  Tip leakage flow  Sweeping jet actuator  Unsteady flows  Linear turbine cascade

摘要:

为控制涡轮叶栅中叶顶间隙泄漏流动和改善涡轮气动性能，将扫频式射流器(SJA)作为一种主动流动控制方法应用在涡轮叶栅的研究中。通过非定常数值计算，分析了SJA对涡轮叶栅叶顶间隙流动的作用过程以及作用机理，并且研究了不同工况下SJA对涡轮叶顶流场改善效果以及不同频率的SJA对叶顶流场的影响。结果表明：通过在涡轮叶栅上端壁增加单个SJA装置，可以有效地延迟上端壁的流动分离，其中最佳方案射流流量仅为进口总流量的0.35%，涡轮叶栅出口截面总压损失系数减少了11.48%。存在着最佳的频率284Hz，使SJA装置对流场的作用效果最佳，有效地改善了涡轮叶栅内的间隙流动。

Abstract:

For the purpose of controlling blade tip clearance flow in turbine cascade and improving its aerodynamic performance, sweeping jet actuator (SJA) has been introduced as a positive flow control method in the research on turbine cascade. Through unsteady calculation of the model, the effects of SJA on the interaction process and mechanisms of turbine cascade tip clearance flow are analyzed, as well as the effects of SJA on the improvement of turbine tip clearance flow field under different operating condition and the effects of SJA frequency on turbine tip clearance flow field. The results show that flow separation could be effectively delayed with employing single SJA on casing. Among all cases, the optimal case could reduce the total pressure loss coefficient by 11.48% with injecting flow mass flow rate only 0.35% of the inlet mass flow rate. 284Hz is the optimal SJA frequency that could improve the flow field most and effectively improve tip clearance flow in turbine cascade.