The unsteady surface pressures on the rotor blades of a single-stage low-speed axial compressor were measured by means of mounting micro-sensors on the surface the blades.The effects of up-stream blade wakes on the spectrum of rotor blades unsteady surface pressure were analyzed.On the rotor blade pressure surface

the dominant frequencies of unsteady surface pressure are the up-stream blade wake passing frequency and its harmonics

and the amplitudes of pressure fluctuations decrease from leading edge to trailing edge.However

on the blade suction side from leading edge to trailing edge

the amplitudes of pressure fluctuations increase at the fore part where flow accelerates and decrease at the rare part where flow decelerates.Flow separation produces pressure fluctuations of large amplitudes

possibly with the dominant frequencies differ from up-stream blade wake passing frequency and its harmonics.