Experimental Study of Gas Injected Bubble Growth from Submerged Orifices

Abstract

This work investigates the mechanism of adiabatic gasbubblegrowth from submergedorifices with the view of elucidating the interdependence of the bubble shape and the pressure field during growth and departure. Air injection flow rates between 10 mlph and 100 mlph have been tested for orifices of diameters 0.58 mm, 1.05 mm and 1.6 mm. The force field around single isolated bubbles during growth and detachment has been investigated experimentally with the aid of high speed photography and detailed image processing and measurement of the internal bubble pressure. Different flow rates have been compared in order to elucidate dynamic effects. Combining measurements of the instantaneous gas pressure, measurements of the local curvature and the Young?Laplace equation has allowed the estimation of the liquid pressure field acting on the gas?liquid interface over the entire bubble surface. These have subsequently been decomposed into constitutive components such as buoyancy, contact pressure, capillary and the dynamic pressure forces.