Original articles: Experimental study on microbubble ejection method for frictional Drag reduction

摘要

The formation of air bubbles ejected through a single hole in a flat plate was observed in uniform flow of 2- 10 m/s. It was confirmed that the size of the air bubbles was governed by main flow velocity and air flow rate. According to previous experiments, the size of the bubbles is an important factor in frictional drag reduction by microbubble ejection. Usually bubbles larger than a certain diameter (for example 1 mm) have no effect on frictional drag reduction. Three dif- ferent methods were proposed and tested to generate smaller bubbles.