涡轮叶栅叶顶间隙冷气掺混数值模拟

Numerical Simulation for Coolant Mixing on the Tip of Turbine Cascade

采用具有三阶精度TVD性质的有限差分格式计算方法,对一具有真实冷气孔形状的涡轮级叶顶间隙冷气掺混流场进行了全三维N-S方程数值模拟,分析了在1%和2%间隙下冷气射流与间隙流动相互作用的运动机理以及冷气射流对间隙和叶栅流场的影响。结果表明,冷气喷射使得泄漏流动速度降低,在小间隙下运动轨迹偏转以及气动参数的变化都非常明显,轮榖表面可以获得低温保护。在大间隙下叶顶表面获得更好的冷却效果。

Finite difference scheme with third order precision and TVD property was employed in this paper. Investigation of mechanism of the coolant ejection flow field was performed on the tip of turbine cascade with six cooling holes by three dimensional N-S solver. Interaction between coolant ejection and tip clearance flow was expounded and influence of coolant ejection on the tip clearance flow and temperature distribution was discussed in 1% and 2% blade tip gaps respectively. The results show that the velocity of leakage flow is reduced due to the coolant ejection. The deflection of leakage vortex and the change of aerodynamic parameters are both obvious, and the shroud surface is under protection of low temperature at1% tip gap. Higher adiabatic effectiveness is observed at 2% tip gap under a constant blowing ratio.