Frequency spectrum analysis of unsteady pressure field in tip clearance unsteady flow

Thoroughly researches to unsteady pressure pulse in tip clearance flow of rotor and its changes are extremely significant to further improving the efficiency of the compressor. The time-domain wave of unsteady pressure fluctuation were transformed into frequency spectral curves by Fast Fourier Transform (FFT) in this paper to investigate the relation of rotor speed, outlet pressure and axial position to the frequency spectrum performance, associated with aerodynamic performance and flow stability of compressor. Experiments show that dominant frequency of tip clearance unsteady pressure pulsation increases with the increase of the rotor speed, but less reaction to the outlet pressure. Peak value in dominant frequency increases with the increase of the rotor speed or the decrease of the outlet pressure. Compared with the leading edges and trailing edge of blade, the peak value in dominant frequency achieves maximum at the center of bladetip. Some research results obtained could be help of understanding of pressure fluctuation effects to other rotational flow in turbomachinery.