Experimental study on flow characteristics in water under impinging air jets

The flow characteristics in water in the tank under impinging air jets was experimentally investigated using the technique of flow visualization. The water surface depression was observed and velocities in water were measured with a particle image velocimetry (PIV) by varying the velocity of a jet and the distance between the nozzle and the impinging surface. From the experiments, it was confirmed that convective flows were formed in the flow inside the water tank by the impinging jets. The results of the experiment showed that from no concavity at the water surface, the concavity began to form from the impinging area, followed by a wave, and then, depending on the conditions, either a large wave formed over the entire water surface or the concavity oscillated, which could be classified into five states. It was also found that there is a suitable combination of conditions for the velocity of a jet and nozzle-to-water surface distance under which convective flow is enhanced.