TURBULENCE INTENSITY IN THE VORTEX SETTLING TANK

Experimental research was undertaken to investigate changes in flow velocity and turbulenceintensity in a vortex settling tank as a result of increasing flow rate. Two studies were conductedfor two different flow rates through the settling tank. The changes in the flow turbulence structurewere analysed at two depths of the settling tank based on the measured instantaneous flowvelocities. The instantaneous velocities were measured using a three-component acoustic Dopplervelocity meter. Changes in values and distributions of velocity and turbulence intensity in thevortex settling tank were presented. It was observed that a twofold increase in flow caused an up toa threefold increase in the average flow velocity near the settling tank walls, a twofold increase inthe turbulence intensity near the settling tank walls, and an increase in zones of local turbulence.In these zones, the increase in the gradient of turbulence intensity values is much greater than inthe others. The zone of turbulence with maximum values occurs on the left side of the settling tanknear the outlet deflector. The presented changes in the turbulence structure negatively affect theefficiency of the settling tank by increasing the values of velocity and turbulence intensity.