Experimental research on unsteady blade surface pressure of axial compressor

The unsteady surface pressure on stator blade of an axial compressor was measured by means of mounting micro-sensors onto blades surface.The unsteady blade surface pressure was analyzed.There are different factors to play decisive roles on the unsteady surface pressure and unsteady force with the decrease of flow coefficient.Before stall,unsteady blade surface pressure depends on the wake and potential perturbation of adjacent blade row.But after stall,unsteady blade surface pressure depends on the stall cells.Before stall,maximum amplitude of unsteady blade surface pressure and unsteady force occurs at the flow coefficient of maximum total pressure rise.However,after stall,the amplitude of unsteady surface pressure and unsteady force will be much greater than at the maximum total pressure rise.On the other hand,the frequencies of unsteady surface pressure and unsteady force change with the decrease of flow coefficient.Before stall,the dominant frequencies are represented by blade-passing frequency and its harmonics,but after stall,the dominant frequencies are represented by stall cell passing frequency.