Experimental investigation on pressure oscillations caused by direct contact condensation of sonic steam jet

•Pressure oscillations of sonic steam jet with high steam flux were investigated.•Theoretical model on pressure oscillation amplitude was set up.•The pressure oscillation variation with the x/de and r/de was investigated. An experimental study has been carried out to investigate the pressure oscillation of the sonic steam jet in a pool. The exit diameter of the nozzle was 8mm and the steam mass flux was 298–865kg/(m2s), water temperature 20–70°C. The dominant frequency and amplitude of pressure oscillation have been analyzed. A theoretical model on pressure oscillation amplitude was set up and a semi-empirical correlation was given to predict the dimensionless R.M.S (root mean square) amplitude of pressure oscillation. The pressure oscillation is mainly caused by the variation of steam speed δu, heat transfer coefficient δh and net steam-water interface δS. The dominant frequency of the pressure oscillation decreased with the increase of the water temperature while increased in CO region and decreased in SC region with the increase of the steam mass flux. The amplitude of the pressure oscillation is inversely proportional to the dominant frequency. The dominant frequencies did not change with the variation of x/de and r/de. But the amplitudes decreased with the increase of x/de and r/de. An empirical correlation was suggested to predict the dimensionless R.M.S amplitude based on the experimental data. The predictions agreed well with the experiments, and the discrepancies were within ±30%.