Effects of Coriolis force on Complex Turbulent Flow Field in Compressor Rotor

通过对角流转子叶尖泄漏流与轴流转子叶尖泄漏流的实验与计算结果对比，研究了科氏力即流面倾角对压气机转子湍流流场的影响。研究发现，在斜流转子中，叶尖泄漏涡的“击穿”发生在通道尾部。“涡击穿”使叶尖泄漏涡的性质发生了显著的变化：涡核消失，涡大幅膨胀，涡内出现低相对速度区。这些变化导致叶尖泄漏流动的表现与轴流转子有很大不同：1 .由于涡量集中的涡核消失，在斜流转子下游没有观察到叶尖泄漏涡的卷起涡芯的消失导致涡量集中引起的压力梯度的损失，从而使旋翼流道尾部机匣壁上的压力槽消失涡旋核心的消失似乎导致了斜流转子的噪声水平比轴流转子低得多由于低相对速度区与反向流动引起的泄漏涡膨胀较大，泄漏流产生的低能流体从机匣向外扩散至约半跨。因此，与轴流转子相比，机匣壁面边界层的增长要大得多在斜流转子的下游，由于低相对速度区域的流体像尾迹一样具有较大的绝对速度的切向分量，因此在机匣壁面边界层内绝对切向速度显著增加机匣壁面边界层的大幅度增长导致效率随叶顶间隙的大幅度降低，其效率降低率约为轴流转子的3倍。少

Effects of Coriolis force, namely, stream surface inclination on turbulent flow fields in compressor rotors have been investigated by comparing experimental and computational results of the tip leakage flow in a diagonal flow rotor with those in an axial flow rotor. It was found out that "breakdown" of the tip leakage vortex occurs at the aft part of the passage in the diagonal flow rotor. The "vortex breakdown" causes significant changes in the nature of the tip leakage vortex : disappearance of the vortex core, large expansion of the vortex, and appearance of low relative velocity region in the vortex. These changes result in the following behavior of the tip leakage flow substantially different from that in the axial flow rotor :1 Because of the disappearance of the vortex core with the concentrated vorticity, the rolling-up of the tip leakage vortex is not observed downstream of the diagonal flow rotor.2 The disappearance of the vortex core leads to the loss of the pressure gradien … More t induced by the concentrated vorticity, so that the pressure trough vanishes from the casing wall at the aft part of the rotor passage.3 The disappearance of the vortex core seems to results in the fact that the noise level of the diagonal flow rotor is considerably low, compared with the axial one.4 Because of the large expansion of the leakage vortex caused by the low relative velocity region with reverse flow, the low-energy fluid due to the leakage flow is spread out from the casing to about a half of span. As a result, much larger growth of the casing wall boundary layr occurs, compared with the axial flow rotor.5 Downstream of the diagonal flow rotor, the absolute tangential velocity increases considerably in the casing wall boundary layr, because the fluid in the low relative velocity region has a large tangential component of the absolute velocity, like the wake.6 The large growth of the casing wall boundary layr causes large reduction of efficiency with the tip clearance : the reducing rate of efficiency is about three times as large as that of the axial flow rotor. Less