组合压气机中尾迹与势流同频/异频干涉的叠加特性

Superposition of Influences from Wake and Potential Field with Equal and Unequal Frequency in an Axial-Radial Combined Compressor

为揭示多级压气机中上下游叶轮对中间叶片叠加气动影响特性,阐述不同叠加干涉情况下下游叶轮进气角度变化,采用数值方法模拟了一级轴流和一级离心组成的组合压气机非定常流场。详细讨论了上游动叶尾迹和下游动叶势流对中间导流叶栅段气流非定常流动的异频和同频叠加干涉特性,依据计算结果,直观地展示了静叶通道中两种干涉间相互激励和抑制作用的位置和时间,与数学公式的推导结果相互印证。研究结果表明:当上下游动叶对中间静叶段异频干涉时,干涉的激励、抑制区域的轴向位置随时间发生变化;当上下游动叶对中间静叶干涉频率相同时,干涉的相互激励、抑制区域的轴向位置不随时间发生变化,但干涉的激励、抑制区域的轴向位置受时序位置影响。另外,上游动叶尾迹与下游离心叶轮势流的不同叠加情况,决定着下游离心叶轮进口相对气流角的大小及波动幅值。

A numerical investigation in an axial-radial combined compressor was performed to study the superposition of rotor/stator and stator/rotor interaction and to indicate the variations of the flow angle at inlet of the downstream rotor. Three configurations, R/S/R rig with unequal moving blade numbers, R/S rig and R/S/R rig with identical moving blade numbers, were included in this research project. Efforts were focused on the superposed interaction in the stator channel, specifically the changes in the deterministic kinetic energy caused by changing blade numbers and rotor clocking. Besides, a useful mathematical model for analyzing these changes was presented. Results show that, for the compressor with unequal moving blade numbers, the position of the excitation/suppression changes with time whereas it keeps fixed position for the rig with identical moving blade numbers. But the position can be modulated by clocking when the rotors have equal blade numbers. In addition, the blade numbers and clocking position also decide the inlet flow angle for downstream radial rotor.