Mutual interaction of a two-phase turbulent/bubbly submerged water jet with a single-phase jet for the measurement of the enhanced hydrodynamic near-field pressure spectrum

Abstract

The interaction of mutually perpendicular submerged turbulent water jets is studied from the measurement of the enhanced hydrodynamic near-field pressure spectrum. One jet is a conventional single-phase, free turbulent shear flow circular jet, while the other jet is a two-phase bubbly jet of similar construction. The overlap region is located at four-nozzle diameters (4D) away from each orifice. A small hydrophone located outside the overlap region (4D away from the interaction region and 45 deg from the jet axis) measures the near-field pressure spectrum. Very small gas bubbles are required for this two-phase turbulent jet. They are generated by pressurized carbonated water flowing through a thin circular nozzle plate having an array of small holes. These CO2 gas bubbles are mixed within the entrance to the tapered jet nozzle. Alternatively, bubbles are generated by pressurized N2 gas passing through a fritted disk housed in a Buchner funnel located near the nozzle entrance. Spectra are measured and compared for different void fractions and different Reynolds numbers that are based on the jet diameter.