超高负荷低压涡轮叶型边界层被动控制

Boundary Layer Passive Control of an Ultra-High-Lift Low-Pressure Turbine Blade

关键词:  超高负荷  低雷诺数  被动控制方式  叶型损失

Key words:  Ultra-high-lift  Low Reynolds number  Passive control methods  Profile loss

摘要:

应用商用流体计算软件求解定常雷诺平均N-S方程组耦合Lantry-Menter转捩模型,对来流湍流度1.5%,不同进口雷诺数下,前加载超高负荷低压涡轮叶型进行了数值模拟。在与相关实验数据对比的基础上,研究了三种被动控制方式的控制效果与控制机理。结果表明:弧形凹槽的最佳开槽位置在分离点,最佳深宽比为0.15,表面拌线和矩形条的最佳加载位置在速度峰值点与分离点的中点；控制方式能否有效与其增加的掺混损失和减少的分离损失有关；三种控制方式均通过产生小漩涡来增加低能流体与高能流体之间的交换,从而加速转捩减小分离泡降低叶型损失。 

Abstract:

A numerical study was conducted to improve the performance of a forward-loaded ultra-high-lift low-pressure blade at low Reynolds numbers and FSTI(freestream turbulence intensity)being 1.5%. Based on Langtry-Menter transition model, the development of the boundary layer on the ultra-high-lift low-pressure blade was simulated by using commercial CFD code to solve the URANS equations. The comparisons of simulated values with the available experimental data show that the bubble length and thickness are well simulated. Three different types of surface trips i.e. groove, wire and step, were investigated to further improve the blade performance. The numerical results show that the optimum location of the groove is at the separation onset location and the optimum depth ratio width is 0.15, for the wire and step its’ optimum location is midway between the blade suction peak and the separation onset location. The loss reduction is a compromise between the positive effects from the separation bubble reduction and the negative effects from having a larger dilution zone. A vortex was observed in the groove and at the front of the wire and step,so it hastened the transition process but couldn’t induce transition immediately. 