Experimental and Numerical Analysis of Rotor–Rotor Interaction Characteristics inside a Multistage Transonic Axial Compressor

Serving as a key component of the core engine, the high-load axial compressor is expected to have high performance, which determines several critical parameter levels of the aero-engine. The unsteady effect on the performance induced by the interaction among different rotors should not be ignored during the design of a high-load compressor. The interaction between R1 (the first rotor row) and R2 (the second rotor row) rotors of a transonic axial compressor was measured in detail using high-frequency pressure fluctuation sensors, aiming to reveal the evolution and distribution characteristics of the R1 sweep effect inside the R2 passage. The results show that near choke and design points, the interaction between the R1 oblique shock wave at the leading edge and the high-pressure region on the blade pressure side triggers the R1-2BPF (blade passing frequency) disturbance, which is different from the traditional harmonic of the blade wake disturbance. A ‘long tail’ flow structure, which indicates the major influence of the R1 shock wave, fluctuation obviously reaches the exit of R1 and influences the upper part of S1 and R2. The combination of the R1-2BPF and the R1-1BPF (mainly caused by the R1 wake disturbance) influences the R2 flow field significantly, and both of them sharply grow at the middle and rear parts of the R2 passage where the strength of the two disturbances increases by 24% and 68%, respectively, compared to the leading edge of R2. Moreover, the circumferential non-uniformity of the R1-1BPF and R1-2BPF disturbances significantly increase at some locations of the R2 passage compared to the R1 exit, which is attributed to the relative clocking positions of the R1 and R2 blades.