Influence of endwall profiling on purge flow and mainstream flow in the high-pressure turbine
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摘要:
轮缘封严流在保证高压涡轮正常工作的同时也会与通道主流发生相互作用,导致掺混损失增加。以某典型高压涡轮叶栅为研究对象,采用数值模拟的方法,开展了轮缘封严流与主流相互影响机理研究。在此基础之上,探讨了非轴对称端壁对涡轮端区二次流的影响,在不同封严流量下详细分析了涡轮内部损失变化情况。在封严流流量比为0.7%时,非轴对称端壁减弱了端区横向压力梯度,削弱了封严泄漏涡和马蹄涡压力面分支横向迁移的驱动力,延缓了通道涡的形成;当封严流流量比增大到1.3%时,端区二次流的强度更大,非轴对称端壁对端区流动损失仍然具有明显的抑制作用。必须指出的是非轴对称端壁可以削弱叶片吸力面局部的逆压梯度,抑制角区流动分离。
Abstract:Because of the interaction between mainstream flow and the purge flow that can ensure the security of the engine, the flow loss increased accordingly. The typical high-pressure turbine cascade was selected, and the interaction mechanism between the purge flow and mainstream flow in the high-pressure turbine was studied by numerical simulation. On this basis, the influence of non-axisymmetric endwall on secondary flow was deeply discussed and the variation of the flow loss of turbine was analyzed in detail under two different purge flow conditions. When the mass flow ratio of the purge flow was 0.7%, the non-axisymmetrical endwall weakened the transverse pressure gradient near the hub and the driving force of the migration of the pressure side leg of horseshoe vortex and leakage vortex, and delayed the passage vortex formation. When the mass flow ratio of the purge flow increased to 1.3%, the intensity of secondary flow near the hub became stronger, but the non-axisymmetric endwall still had great effect on decreasing the flow loss. It must be noted that the non-axisymmetrical endwall can also weaken the local adverse pressure gradient on the blade suction side and inhibit flow separation in the corner area.
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Key words:
- high-pressure turbine /
- secondary flow /
- purge flow /
- non-axisymmetric endwall /
- total pressure loss
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表 1 叶型几何和气动参数
Table 1. Geometry and aerodynamics parameters of the blade
参数 数值 弦长/mm 61.08 轴向弦长/mm 43.92 栅距/mm 50.445 叶高/mm 120 攻角/(°) 1.4 进口气流角/(°) 44 出口气流角/(°) 18.47 进口马赫数 0.26 出口马赫数 0.89 -
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