尾迹对涡轮叶栅边界层转捩的影响

Effects of Wake on Boundary Layer Transition of Turbine Cascade

Key words:  Transition  Wake  Boundary layer  Turbine cascade  Intermittency factor  Unsteady

摘要:

为研究周期性尾迹对下游涡轮叶栅边界层转捩的影响机理，并验证[γ-Reθ]转捩模型在非定常计算中的适用性，在自行开发的CFD程序上实现了该模型，对带有尾迹发生器的T106D-EIZ涡轮叶栅进行数值模拟；对比分析了实验数据与数值模拟的结果，并对流动机理进行阐述。主要结论如下:[γ-Reθ]转捩模型对周期性尾迹影响下的边界层转捩预测得较为准确，转捩位置随时间的变化规律及幅值均与实验值符合得很好；尾迹的时均作用是使吸力面转捩位置向尾缘移动，相比于无尾迹情况其移动距离约为5%轴向弦长；尾迹使吸力面阻力系数时均值较无尾迹情况增加约40%，同时减弱了分离泡的强度，但对分离泡的位置影响不大。

Abstract:

For the instance of researching the mechanism of the effects of periodic wakes on boundary layer transition of downstream turbine blade，and verifying the applicability of[γ-Reθ]transition model in the unsteady simulation，an internal CFD code was used to implement this model to make a numerical simulation of T106D-EIZ turbine cascade，which was with wake generators. Comparative analyses for numerical results and experimental data were made and some related flow mechanism was described，getting main conclusions as follows: [γ-Reθ]performs well in predicting the effects of periodic wakes on boundary layer transition，changes of transition location with time and the moving amplitude are both in good agreement with the experimental values. Time averaged effect of the wake tends to shift the transition position down-stream，for the length about 5% axial chord compared with the no-wake condition. Existence of the wakes increase time averaged friction coefficient for about 40%，and weaken the strength of separation bubble at the same time，while，little influence is made on the position of separation bubble.