Experimental investigation on interfacial behavior and its associated pressure oscillation in steam jet condensation in subcooled water flow

An experimental study is performed to investigate mechanisms of the interfacial behavior and their associated pressure oscillations in steam jet condensation in subcooled water flow in a vertical pipe. The transient interfacial behavior of the condensing jet is first captured by a high speed camera, and then its parameters are quantitatively computed by using digital image processing technology. Pressure oscillations associated with jet interfacial evolutions are acquired by flush mounted pressure transducers with high frequency response on the wall. The interfacial behavior of the jet at two typical condensation regimes, i.e., bubbling regime and jetting regime, and their corresponding quantitative temporal and spatial evolutions of radial and axial interfaces and pressure oscillations are analyzed. With increase of steam mass flux, interfacial oscillations and pressure oscillations reach local maximum near the sonic point, and they remain almost unchanged after entering the supersonic region. Dominant frequencies of radial and axial interfacial oscillations and those of pressure oscillations are almost the same at subsonic and sonic conditions, while the dominant frequency disappears at supersonic conditions. Very strong correlations between interfacial oscillations and pressure oscillations are quantified through the oscillation intensity and correlation coefficient and also the power spectrum density, which confirms quantitatively that pressure oscillations are induced by interfacial oscillations of the jet.