A study of speed ratio affecting the performance of a contra-rotating axial compressor

The performance and detailed flow structure of a counter-rotating compressor under different rotating speed and typical working condition were experimentally and numerically investigated. Numerical results preliminarily showed that the total pressure ratio performance agreed well with experimental data, when the calculated peak efficiency was a little bigger than the experimental one. With optimized speed ratio, the peak isentropic efficiency can be increased with minor reduction of the total pressure ratio and safe margin. Flow reversal fist occurred at the start section of the outlet guide vane and it covered nearly 40 per cent area of the whole flow at the stall point when the rotational speed ratio of rotor 1 and rotor 2 were greater than or equal to 1, and it caused the compressor operate in the stall point. First, however, the flow separation and great range low-energy flow occurred at the 30 per cent span range of s rotor blade-tip near stall point, which was the main reason for the compressor stall when the speed ratio is less than 1. Rotor 2 worked at a greater incidence angle because of the separation at the trailing edge of rotor 1.