Study of an Air Cavity in Water Tunnel

Other conference contribution, 2011

To study the resistance reduction of an air cavity for a displacement vessels, a simplified model of a cavity is simulated using computational fluid dynamics(CFD) and model tests. Initial CFD computation have been performed to design the model tests and the model tests will subsequently be used to validate the CFD simulations. The length of the cavity is approximately 2.5 times the expected wavelength of the water-air interface and the Froude number based on the cavity length is 0.2. Parameters like pressure play important role in the wave’s shape and the stability of the water surface inside the cavity. Computation shows that the amplitude of the wave is sensitive to the air pressure in the cavity and the re-attachment of the water to the rear end of the cavity has a close correlation to the inlet air pressure. The ultimate goal of this investigation is to minimize air supply while reducing resistance in/around the cavity, but equally important is it to gain a more basic understanding of the air-cavity’s behavior and possible additional resistance components.