An Experimental Study of the Flow Field and Air Distribution Strategy on a Flat Plate with Air Injection


Department of Naval Architecture Engineering, Naval University of Engineering, Wuhan 430033, China


In order to investigate the effect of air flow rate distribution on plate flow field characteristics, an experiment of plate with air injection was conducted in a high speed towing tank. The influence of air flow rate distribution at longitudinal and transverse on drag reduction and the morphology of air layer were investigated. The result show that the air-water mixed flow under the plate surface is mainly affected by the velocity of flow and air flow rate. When the non-dimensionalzed air flow rate coefficient is less than 1.554 (Cq≤1.554), the mixed flow mainly has a bubbly flow; when the non-dimensionalized air flow rate coefficient is greater than 2.331 (Cq≥2.331), the mixed flow has an air-water stratified flow; Otherwise, there is a transitional flow that is both bubbly and stratified. The local friction drag reduction at the lower surface of the plate near the injection is 100%. The drag reduction rate of total resistance for the lower surface of flat plate will reach 60.65% when improves the strategies of air injection and the air ratio is 1:4:1 in the header air injection device. The joint air injection of header and central device has no contribution to the drag reduction rate of total resistance.