A quantification of penetration length of steam jet condensation in turbulent water flow in a vertical pipe

An experimental research is performed to investigate the penetration length of steam jet condensation in turbulent water flow in a vertical pipe. The penetration length of the condensing jet, with steam mass velocities ranging from subsonic to supersonic, was measured via utilizing a visualization window and a high-speed camera. At low steam flow rate a steam bubble plume forms, while at relatively high flow rate the bubbles in the plume coalesce and a steam jet is produced. Quantitative analyses of the interface behavior of the condensing jet are performed by exploring the transient and statistical characteristics of the jet penetration length. The waveforms of the transient jet penetration length exhibit that in the bubbling regime the period is approximately constant, while in the jetting regime the period varies a lot. The statistical analysis of the transient jet penetration length confirms that significant variations of the power distribution function (PDF) and power spectrum density (PSD) between the bubbling and jetting regimes occur at the transonic condition. The ratio of steam mass flux to critical steam mass flux at ambient pressure is found to have good linearity with the mean of the jet penetration length. And a linear correlation is fitted with a maximum absolute deviation of 5.5% between the measured and predicted values of mean of the jet penetration length. The relative unsteadiness of jet penetration length, defined as the ratio of the standard deviation to mean of transient penetration length, is approximately invariable in the bubbling and jetting regime. The bubbling regime contains more relative unsteadiness, while the jetting regime yield less relative unsteadiness. Because absolute instability exists in the subsonic region while no absolute instability occurs in the supersonic region, the transition from the bubbling to jetting regime occurs in the transonic region.