Mixing Evaluation of a Vertical Bubble-driven Plume with Various Types of Air Injection Nozzles

Abstract

    Mixing and entrainment of vertical bubbly plumes with 4 vaious types of air injection nozzles have been evaluated by simultaneous velocity-temperature measurements. Local velocity and temperature have been measured by a Laser Doppler Velocimetry(LDV) and thermistor probes respectively. The porous plug nozzle, which generates swarm of small bubbles, produces smaller scalar fluctuation and less contributes mixing and entrainment than any other nozzles. The work quantifies the expected tendency that the mixing is improved by the larger velocity fluctuations produced by bigger bubbles.