EXPERIMENTS FOR FINE AIR BUBBLE PRODUCTION IN LIQUIDS USING EJECTORS

Experiments were conducted to investigate the effects of various factors on the performance of an ejector as a device for producing fine air bubbles in liquids and to obtain data for optimum design of the ejector such as the principal dimensions of the nozzle and the mixing tube, the optimum velocity of the liquid jet, etc. As a result: 1) the design parameters were determined for the optimum dimensions of the ejector (i.e., the distance between the nozzle and the mixing tube is 3 to 5 mm, the difference between the diameters of the mixing tube and the nozzle is 0.2 to 0.4 mm, etc.) and a cloud of air bubbles 10 to 200 mum in diameter could be continuously produced in water, salad oil, and a tamarind water solution; 2) the relation between the Weber number of the liquid jet and the Reynolds number of the pipetted air was expressed as We = b Re(m); and 3) the equation for predicting the ratio of flow rates zeta, the ratio of the flow rate of the pipetted air, Q(g), to that of liquid jet, Q(L), was derived from the relation between We number and Re number.