进口总压畸变条件下离心压气机流动失稳特性的数值研究

Numerical Study on Flow Instability Characteristics of Centrifugal Compressor with Inlet Total Pressure Distortion

采用数值模拟方法对比分析了畸变进口与均匀进口条件下离心压气机的气动性能。结果发现,离心压气机展现出一定的抗畸变能力,总压畸变对压气机整体性能未造成显著影响。进一步的分析表明,在均匀来流条件下,随着流量的降低,主叶片和分流叶片之间的低速区逐渐向叶顶区域发展,阻碍主流流动,相互排挤并由叶顶间隙溢出;畸变来流条件下,在近失速工况点时,叶顶沿流向流动出现局部负速度,叶顶泄漏涡前移,在进口畸变产生的低压区内吸力面流动分离增大,进而演变出龙卷风涡阻塞流道,并影响到相邻叶片,引发前缘溢流;通过Q-准则方法发现,在畸变来流条件下,近失速工况下的涡结构分为前缘失速涡、叶顶间隙泄漏涡、通道涡和前缘溢出涡。

The aerodynamic performance of centrifugal compressor under the condition of distorted inlet and uniform inlet is compared and analyzed by numerical simulation method.The results show that the total pressure distortion studied does not have a significant impact on the integrity of the compressor performance,and the centrifugal compressor exhibits a certain antidistortion capability.Further analysis shows that under the uniform inlet condition,the low-speed area between the main blade and the splitter blade gradually develops to the tip area with the decrease of flow rate,which hinders the mainstream flow,pushes out each other and overflows from the tip gap.Under the condition of distorted inlet flow,the blade tip has a local negative velocity in the flow direction near the stall operating point,the tip leakage vortex moves forward,and the flow separation on the suction surface increases in the low pressure area generated by the inlet distortion,evolves tornado vortex blocking the flow channel,affects the adjacent blades causing leading edge overflow.It is also found that under the condition of distorted inflow,the vortex structure near stall conditions includes leading edge stall vortex,tip clearance leakage vortex,channel vortex and leading edge overflow vortex.