弧形端壁造型对不带冠涡轮气动性能的影响

Effects of Arcing Endwall Contouring on Aerodynamic Performances of an Unshrouded Axial Turbine

关键词:  涡轮  间隙泄漏  端壁造型  弧形

Key words:  Turbine  Tip leakage  Endwall contouring  Arc

摘要:

采用商用计算流体力学软件CFX，湍流模型采用标准 k - w 两方程湍流模型，叶型为单涡轮动叶叶片，应用数值模拟方法研究了弧形端壁造型对动叶泄漏流动及涡轮气动性能的影响。数值研究结果表明:适当优化的弧形端壁造型可以改善泄漏涡和通道涡作用状况、提高出口总压和改善气流角分布、降低叶顶间隙泄漏和提高效率。最优端壁造型可以减少间隙泄漏0.27%，提高效率0.77%。在变攻角下，最优端壁造型效率最高点出现在设计攻角下，但攻角变化越大，间隙泄漏流动越少。

Abstract:

CFX simulations were performed by solving steady compressible Reynolds-averaged N-S equations in conjunction with the standard k - w two-equation turbulence model adopted in this study. The blade calculated was a rotor blade in a gas turbine. The numerical simulation was performed to investigate the effects of arcing endwall contouring on blade aerodynamic performances and tip leakage flow. The results show that the arcing endwall contouring can weaken passage vortex and tip leakage vortex，improve the flow angle condition，reduce the mass flow of tip leakage flow，raise outlet total pressure and the efficiency of the turbine．The optimized arcing endwall contouring reduces the blade tip leakage flow by 0.27% and increases the turbine efficiency by 0.77% compared with original turbine. The optimized arcing endwall contouring provides the largest efficiency increase when the inlet flow direction incidence is at the design incidence. When incidence change becomes larger，the blade tip leakage flow becomes smaller.