叶尖间隙及转速增大对对转压气机非定常流场的影响研究

A two-stage counter-rotating axial-flow compressor (CRAC) was studied and the unsteady flow characteristics induced by the coupling of blade tip clearance size (TCS) and rotational speed changes were investigated. Based on numerical simulation results， the proper orthogonal decomposition (POD) method was employed to extract the POD modal distribution patterns. Further analysis on the flow characteristics of the blade TCS under near-stall conditions was conducted. Numerical and FFT results showed that as the blade TCS increased，the leakage flow and the fragmentation of blade tip leakage vortex (TLV) intensified，leading to an enlargement of the range of unsteady fluctuations and a reduction in fluctuation intensity. The frequency of blade tip leakage flow (TLF) fluctuations in the rear rotor (R2) increased. The interference between the blade TLF overflowing channel of R2 and the leading edge of adjacent blades was attributed to the sudden increase in unsteadiness at the leading edge. The POD analysis confirmed the above conclusions and revealed the reasons for the static pressure fluctuation region on the blade surface. It was also found that an increase in blade TCS resulted in a decrease in the dominant modal structure of the three-dimensional flow field in the front rotor (R1)， and the higher-order modal structure of R1 migrated radially towards the blade root. As the rotational speed increased，the interference between the upstream and downstream rotors also increased.