轴流压气机转子近失速工况点叶尖区流动非定常性分析

Unsteady behavior of tip clearance flow in an axial flow compressor rotor at near stall condition

关键词:  轴流压气机  间隙流  泄漏涡  叶尖二次涡+

Key words:  Axial compressor  Tip clearance flow  Leakage vortex  Tip secondary vortex+

摘要:

为了揭示某轴流压气机转子近失速工况点叶尖区域流场的非定常变化及其形成机理,采用定常和非定常数值模拟方法对其内部流场进行了全三维的数值模拟。通过和已有的试验测量结果进行对比分析表明,预测的总性能及基元性能与试验结果取得了很好的一致性。近失速工况点的非定常模拟结果表明,压气机的总性能及叶片承受的扭矩出现了周期性的波动,其波动周期约为转子通过频率的2.5倍。进一步详细分析叶尖区流场的瞬态流动结构发现,间隙泄漏涡在近失速工况下出现了泡式破碎,破碎的泄漏涡、主流以及来自相邻叶片的间隙泄漏流相互作用形成了另外一个特征明显的旋涡(命名为叶尖二次涡)。该旋涡的形成、发展和运动是压气机的总性能出现周期性波动的主要原因。

Abstract:

In order to uncover the unsteady behavior of tip clearance flow in an axial flow compressor rotor at near stall condition and its associated flow mechanism,three-dimensional steady and unsteady flow simulations were conducted to analyze the internal flow fields in an axial flow compressor rotor.To validate the numerical results,the predicted total and elemental performance was compared with the available experimental data,and good agreement was achieved.The convergence history of the unsteady simulations at near stall condition showed that parameters,especially rotor efficiency and torque acting on blade,got nearly periodic fluctuation,and the period was about 2.5 blade passing time.By further analyzing the instantaneous flow structure near rotor tip,it was found that tip leakage vortex broken down at near stall condition.The interaction of the breakdown of tip leakage vortex,main flow and the tip leakage flow from the adjacent blade formed another distinct vortex,which was named as tip secondary vortex.The cyclical motion of this vortex was the main source of the periodic variation of the flow total parameters.