叶片安装角对离心压气机扩压器气动性能及失速机理影响研究

Research on the Influence of the Vane Stagger Angle on the Aerodynamic Performance and Stall Mechanism of Centrifugal Compressor Diffuser

为了研究离心压气机扩压器异常叶片对于失速现象的诱发效果,以带有叶扩压器的高速离心压气机为研究对象,通过整体或局部改变扩压器叶片安装角,开展非定常数值模拟研究并与实验结果对比验证,研究叶片安装角改变对离心压气机性能、动态特性以及失速机理的影响规律。研究表明:整体负方向旋转叶片安装角会促使扩压器更加不稳定,旋转角度从-5°到5°,最高效率点对应的质量流量逐渐增大。其中安装角偏转+5°扩压器叶片前缘靠近轮缘壁面发生流动分离,诱使无叶区间产生回流;而偏转-5°扩压器轮毂附近的流动分离主要发生在尾缘,造成扩压器叶片吸力面附近产生大范围回流。单个叶片安装角发生较大偏转(大于10°)时,扩压器比叶轮更早进入失速状态,且失速的机制可能会随着安装角偏移的增大发生改变。

In order to investigate the induced effect of abnormal vanes of centrifugal compressor diffuser on the stall phenomenon, a high-speed centrifugal compressor with vaned diffuser was taken as the research object.The unsteady numerical simulation was carried out by changing the vane stagger angle of the diffuser wholly or partially, and the results were compared with the experimental results to study the influence rule of the vane stagger angle variation on the performance, dynamic characteristics and stall mechanism of the centrifugal compressor.The research results show that selecting the vane stagger angle in the full negative direction will make the diffuser more unstable.From-5° to 5°,the mass flow rate corresponding to the highest efficiency point increases gradually.For the diffuser with the vane stagger angle deflection of +5°,the flow separation near the shroud wall occurs at the leading edge of the diffuser blade, which induces the backflow in the vaneless space.And for the diffuser with the vane stagger angle deflection of-5°,the flow separation near the hub of the diffuser mainly occurs at the trailing edge, resulting in a large range of backflow near the suction surface of the diffuser blade.When the stagger angle deflection of a single blade is larger than 10 degrees, the diffuser stall comes earlier than the impeller, and the stall mechanism may change with the increasement of the stagger angle deflection.