Measurement Technology & Frequency Spectrum Analysis Of Dynamic Pressure In Tip Clearance For Unsteady Flow

Compressor is one of the rotating machinery which used to convert mechanical energy to fluid energy and widely used in dynamic energy, aviation and other fields closely related to the national economy and security. 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 pressure fluctuation of the tip clearance flow of the rotor in a single-stage axial compressor have been measured and analyzed in this paper. The dynamic pressure sensors have been installed on the casing near the tip clearance of the rotor and a high speed dynamic pressure measurement system had been furnished. The time-domain wave of unsteady pressure fluctuation acquired at different work status of the compressor were transformed into frequency spectral curves by Fast Fourier Transform (FFT) in this paper to investigate the relation of rotor speed ,outlet pressure and circumferential position of stator to the frequency spectrum performance, and associated with aerodynamic performance and flow stability of compressor .In order to improve the measurement accuracy, the dynamic pressure measurement system which is composed of the dynamic pressure sensor, acquisition System, measurement and analysis software is detailed in this paper. In addition, in order to reduce the impact of interference sources to the measurement system, interference shielding measures are introduced.The results showed that pressure fluctuation spectrum in unsteady flow field between the leading edge and trailing edge of tip blade contain the firist order spectrum, second order spectrum, third order spectrum etc. Dominant frequency increases with the increase of the rotor speed, but less reaction to the outlet pressure and other work status. Then the impact of rotor speed, outlet pressure and circumferential position of stator to the first, second, third and forth order peak value are mainly analyzed in the paper.With the rotor speed increases, the first and high order peak value showed a increase trend. But have different degree at different flow field. Compared with the leading edges and trailing edge of blade, the peak value achieves maximum at the center...