MEAN FLOW AND TURBULENCE OF WATER IN A CY LINDRICAL VESSEL AGITATED BY BOTTOM AIR INJECTION

Cold model experiments based upon aqueous systems were carried out to study the mean velocity and turbulence intensity in a cylindrical bath . The axial and radial velocity components in the cylindrical bath agi tated by air injection through a centered single-hole bottom nozzle we re measured using a two-dimensional laser Doppler velocimeter. The spa tial mean kinetic energy for the time-averaged component k(m,v) and th at for the turbulence component k(t,v) were obtained. It was found tha t k(m,v) and k(t,v) depended on 0.60 and 0.72 powers of the injected g as flow rate, respectively. The energy supplied by the injected gas in to the bath therefore was more consumed to maintain turbulent motions than to do the mean flow, i.e., the circulating flow as the gas flow r ate increased. Measured values of the spatial mean velocity ($) over b ar V-m,V-v = (2k(m,v))(1/2) were satisfactorily approximated by an emp irical correlation proposed so far, but the dependence of the present ($) over bar V-m,V-v values on the bath depth H-w and bath diameter D was different from this correlation. The spatial mean turbulence inten sity Tu(v) = (k(t,v)/(m,v))(1/2) was above unity under the present exp erimental conditions.