汽轮机叶顶汽封泄漏流动的非定常数值研究

Numerical Study on Unsteady Flow of Tip Seal Leakage in Steam Turbine Rotor Cascades

针对某带有叶顶汽封的300MW汽轮机高压第二压力级及其后相邻的静叶,采用三维非定常数值模拟的方法,研究了叶顶汽封间隙泄漏流的流场结构,叶顶汽封腔室内涡动的频谱特性以及叶顶泄漏流与主流掺混后的流场对下游静叶性能的影响。研究结果表明:叶顶汽封泄漏流动总体随时间呈现周期性波动,汽封间隙出、入口的波动最复杂、频率成分最多。叶顶汽封泄漏流的传播会在下级静叶通道内引起较大的流动损失,泄漏流体中存在径向速度分量,致使掺混后的低能流体逐渐向下级静叶的中叶展处发展,使下级静叶的流场结构发生了改变。

In view of the second high-pressure stage and its adjacent stator blade of a 300 MW steam turbine with blade tip labyrinth seal, a three-dimensional unsteady numerical simulation was adopted to research the structure of the leakage flow field of tip labyrinth seal, the frequency spectrum characteristic of vortex flow in the seal cavity and the effects of downstream stator performance when the leakage flow mixing the mainstream at exit of rotor. The simulation results show that, the leakage flow of tip labyrinth seal is generally characterized as periodic fluctuating. It is in the inlet and outlet seal cavity that the fluctuation is the most complicated and the frequency components are highest. The spreading of the tip seal leakage flow will cause large flow loss in the downstream stator passage, the leakage flow which has high radial velocity component tends to the mid-span in the following stator blade and changes the flow field structure of the downstream stator passage.