高负荷对转压气机中尾迹传播机制研究

Investigation of Wake Propagation in a Highly Loaded

关键词:  尾迹  非线性谐波  叶尖泄漏流  对转压气机  分离涡

Key words:  Wake  Nonlinear harmonic  Tip leakage  Counter-rotating compressor  Separation vortex

摘要:

为了研究尾迹在高负荷对转压气机中的转播机制，采用频域的非线性谐波方法对两级高负荷对转压气机进行了非定常流计算。结果表明:在设计点，通过与定常流计算的结果对比，发现第二级转子在0%～25%的近叶根区域和67%～100%近叶尖区域，非定常得到的效率较小，而在25%~67%的叶中部分非定常的效率更大。研究了尾迹在这三个不同区域的传播规律。结果表明:在叶中，尾迹恢复效应在流动中起到了效率增益的作用；在叶尖，它会与机匣的附面层以及叶尖泄漏流作用，使得端壁附面层增厚和引起泄漏流熵增；在叶根，由端壁附面层产生的马蹄涡和分离涡会影响尾迹的传播，卷吸尾迹并导致尾迹破碎，引起掺混损失。

Abstract:

To study the wake propagation mechanism in the highly loaded counter-rotating compressor，the unsteady simulation has been conducted on a two-stage highly-loaded counter-rotating compressor by the Non-Linear Harmonic(NLH) method. At the design point，it is found that the time-averaged efficiency obtained by using the unsteady simulation is lower at 0～25% span and 67%～100% span than that of the steady simulation，while higher efficiency is observed at 25%～67% span. Further research reveals the different mechanism of wake spread in these three regions. Specifically，at the midspan，the wake recovery plays a dominant role and results in efficiency promotion. Near the blade tip，the wake interacts with the casing boundary layer and tip leakage flow，thickening the casing boundary layer and increasing the entropy of the leakage flow. Near the blade root，the horseshoe vortex and separation vortex influence the wake spread，entraining the wake，giving rise to the wake breakdown and induce mixing losses.