小型离心压气机径向扩压器复杂涡系结构分析

Analysis of Complex Vortex Structure in Radial Diffuser of Small Centrifugal Compressor

对某小型离心压气机进行详细数值模拟,构建径向扩压器复杂涡系结构模型,重点分析设计、堵塞、失速工况下径向扩压器内部复杂涡系结构。研究表明:径向扩压器内部涡系结构主要包括前缘涡、两个通道涡(压力面侧通道涡与吸力面侧通道涡)以及喉部涡;主叶片吸力面的前缘涡是机匣侧低能流体在展向与流向压力梯度作用下形成的,喉部涡是吸力面侧通道涡沿分流叶片前缘的回流与前缘涡构成的;喉部涡在喉部的堆积是导致径向扩压器失速的原因,径向扩压器喉部的激波则是堵塞的原因;随流量的减小,前缘涡的涡核越向相邻主叶片压力面迁移。

Detailed numerical simulation was carried out for a small centrifugal compressor.The complex vortex structure in the radial diffuser with splitter vanes under the design,chock and stall conditions was mainly analyzed and the complex vortex structure model of the radial diffuser was constructed.The research result shows that the internal vortex structure of radial diffuser mainly includes leading edge vortex(LEV),two passage vortexes(passage pressure side and suction side) and throat vortex.The leading edge vortex formed on the suction surface of the main blade is formed by the pressure gradients in the spanwise and flow direction of low energy fluid on the casing side,and the throat vortex is composed of the reverse flow of passage vortex on suction side along the leading edge of splitter vanes and leading edge vortex.The accumulation of the throat vortex at the throat is the cause of the stall of the radial diffuser,and the shock wave at the throat of the radial diffuser is the cause of the chock.The smaller the flow rate is,the closer the vortex core of the leading edge vortex moves toward the pressure surface of the adjacent main blades.