An experimental investigation on the characteristics of submerged horizontal gas jets in liquid ambient

• Horizontal gas jets injected into water ambient through straight tubes is investigated.
• Gas jet structure was carried out using photographic techniques.
• Bubbling, transition and jetting regimes of gas flow have been observed.
• Jet pinch-off and interfacial oscillation were carried out and measured.
• Empirical expressions have been developed for gas jet length, path and expansion angle.

Gas injections into liquid are prevalent in the natural environment and are essential in industrial applications, they can lead to complex flow. The flow structure and processes are essentially unsteady and turbulent. In this study, a set of experiments were carried out to investigate the behavior of horizontal round noncondensing gas jets that discharge in a stagnant water ambient, considering subsonic and sonic jet exit conditions. A flow visualization technique using a CCD camera, which allowed simultaneous measurements, was used to investigate such flows. This technique provided a direct measurement of the interfacial behavior between the gas jet and the liquid ambient. Two different methods, the summation and the statistical one were used to obtain and analyze the experimental results, and we have found that both methods yield almost identical results.The results showed that the injector diameter and the Froude number play an important role in dictating both the jet pinch-off and the jet interface unsteadiness. The maximum location before the jet pinch-off is shown to have a logarithmic relation with the Froude number for all the jet diameters. The jet penetration length was measured in the momentum and buoyant regimes respectively and it was found to be strongly influenced by the nozzle diameter and the Froude number as well as by the mass and momentum flow rates of the injected jet. Jet spreading which is indicative of liquid entrainment is also shown to increase with the Froude number and the injector diameters. Also it was found that the Froude number plays an important role in dictating the expansion jet angle and the jet half-width. These magnitudes were obtained from recorded time-averaged images and finally empirical correlations have been developed to predict these parameters.