An experimental investigation into the hydrodynamic drag reduction of a flat plate using air-fed cavities

The Air-Cavity Ship (ACS) concept is currently being researched as one of the more promising concepts for economical forms of marine transportation. An Air-Cavity Ship uses an air injection system to isolate the bottom part of the ship's wetted surface from the water and thereby to reduce the frictional resistance. The air cavities are generated injecting air at the keel level of a vessel as such the cavities can extend along considerable portions of the hull bottom thus isolating it from the effect of the fluid. The main objective of an effective air cavity system is therefore to maximize the cavity length whilst minimising the air supply. Building on the lack of published experimental research, this paper presents a recent fundamental experimental investigation on air-cavities underneath a flat plane tested in the Emerson Cavitation Tunnel of Newcastle University. The experimental investigation uses this simplified model to understand the correlation of cavity length and volume with potential drag reduction due to the air cavity. The main objective of the research was to generate both fundamental and practical knowledge that furthered the understanding of the air-cavity phenomenon to help its potential application in practice. In addition an attempt was also made to correlate the findings from this experimental study with air-cavity theory and results from limited previous experimental studies performed in other facilities. (C) 2013 Elsevier Ltd. All rights reserved.