Experimental study on the frequency characteristics of self-excited pulsed cavitation jet

Abstract

Periodical dynamic characteristics induced by geometric parameters and operational variables of the self-excited pulsed cavitation jet under the optimum experimental condition is analyzed in the present study. The mechanism of cavitation jet occurrence is interpreted by combining the jet shape, the striking force, and the cavity pressure. With the increase of the inlet pressure, the pulsed frequency increases, and the amplitude decreases. Besides, the pulsed frequency decreases, and the amplitude increases as the oscillation chamber length gets much longer. It reflects that the shape and trend of the waveform are different under different structural parameters and the same operating pressure, while the waveform is the same with the same nozzle structure parameters and the various operating pressures. The peak bandwidth of the waveform is reduced with the increase of the pressure. A long enough peak bandwidth has an essential effect on the striking work operation. Only the peak value of the strike force is kept for an extended period so that it can get an effective strike. The waveform of all dynamic characteristics in the pulsed jet is harmonic. These harmonic waves can be seen as the superposition of several sine waves or cosine waves. It is required that the dominant frequency of pressure oscillation waves is single to avoid the negative influence of noise waves, and then a better effect of striking force is obtained.