涡轮间隙流动结构及其损失产生机理研究

Investigation on Tip Clearance Flow Structure and its Loss Generation Mechanism in Turbine Rotors

应用数值方法和标准κ-ω两方程湍流模型,研究了轴流涡轮叶顶间隙泄漏流场以及端区损失产生机理,同时考虑了进口攻角以及大范围变化间隙的影响.结果表明;间隙内部的泄漏流动情况可以被细分为"攻角驱动型"和"压力驱动型"两种类型,而大多数的泄漏流动则是由叶顶后部的压力驱动型泄漏造成的。动叶通道中间隙泄漏涡和通道涡之间存在着强烈的相互作用,只有在适当大小的间隙下,泄漏涡和通道涡的相互作用才可以被有效利用。

By solving Reynolds-averaged Navier-Stokes equations in conjunction with the standard k -ω two-equation turbulence model, a numerical study was performed to simulate the tip leakage flow field and endwall loss generation mechanism in turbine rotors, considering the effects of both inlet incidence and tip clearance with wide variation. Numerical results show that, the tip leakage flow mechanisms in the tip gap could be defined as ＂incidence-driven＂ and ＂pressure-driven＂ flows, respectively. However, the tip leakage flow was mainly due to the indirect tip leakage caused by the lateral pressure difference across the blade. Since the leakage and passage vortices had a significant interaction in the rotor passage, with the moderate tip clearance height, the interaction between tip leakage and passage vortices could be efficiently utilized to reduce the total losses in turbines.