Prevention of air entrainment during liquid draining using disc-type vortex suppressor

After rotating a cylindrical tank containing a liquid at a constant rotation speed, by draining the liquid freely, an air-core phenomenon (that is, air is entrained into the drain port along a vortex flow) can be forcibly reproduced. This vortex phenomenon occurs very frequently in a variety of actual drainage situations and generally has a negative impact on many industrial devices, including reductions in drain speed, a noise and vibration, and structural damage of turbo machineries. The present study suggests a simple and very effective vortex-suppression device through physically analyzing the causes of the air-core phenomenon. In this study, liquid drainage processes with and without the suggested disc-type vortex suppressor were investigated numerically and experimentally. Through the numerical simulation, the internal flow characteristics have been investigated and the mechanism of the air-core formation has been revealed. As well, the experiments of varying the dimensions of the suggested disc-type vortex suppressor have been carried out. The velocity vector, drain water level, and vorticity distribution were compared for cases with and without the suggested vortex suppressor.