Investigation on pressure wave induced by steam jet condensation in water flow in a vertical pipe

The pressure wave induced by steam jet condensation in water flow in a vertical pipe was investigated experimentally. The inlet steam flow rate and the subcooled water temperature were in the range of 0~500 kg·m^-2·s^-1 and 20~70℃, respectively. The pressure wave caused by the steam jet condensation was captured by several pressure transducers with high frequency, which are mounted on the wall of the vertical pipe. In order to reveal the unsteady features of the pressure wave over a frequency-time plane, the wavelet multi-resolution analysis was first applied to analyze the wall pressure-time signal of experimental data. It was found that the energy of wavelet multi-resolution peaks are observed at levels 4 and 5, which corresponds to scale f=125~250 Hz approximately, while the energy information at the other scale are almost equals to zero. The amplitudes of wavelet multi-resolution are almost zero at relative higher and lower frequency levels. In the levels of 4 and 5 (corresponding to scale f=125~250 Hz approximately), the amplitudes first increase and then decrease with increase of steam mass flux, and the amplitudes increase with water temperature.