Experimental investigation about the effect of non-axisymmetric wake impact on a low speed axial compressor

Non-axisymmetric wake impact experiments were carried out after the best exciting frequency for a low speed axial compressor had been found by axisymmetric wake impact experiments.When the number and circumferential distribution of inlet guide vanes(IGV) are logical, the wakes of non-axisymmetric IGVs can exert beneficial unsteady exciting effect on their downstream rotor flow fields and improve the compressor’s performance.In the present paper,four non-axisymmetric wake impact plans were found working better than the axisymmetric wake impact plan. Compared with the base plan,the best non-axisymmetric plan increased the compressor’s peak efficiency,and the total pressure rise by 1.1 and 2%,and enhanced the stall margin by 4.4%.The main reason why non-axisymmetric plans worked better than the axisymmetric plan was explained as the change of the unsteady exciting signal arising from IGV wakes.Besides the high-frequency components,the non-axisymmetric plan generated a beneficial low-frequency square-wave exciting signal and other secondary frequency components.Compared with the axisymmetric plan,multi-frequency exciting wakes arising from the non-axisymmetric plans are easier to get coupling relation with complex vortices such as clearance vortices,passage vortices and shedding vortices.