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Experimental Study And Numerical Analysis On The Supercavity Of Underwater Vehicle With Different Surface Materials And Structure

Posted on:2017-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:Y J ZhouFull Text:PDF
GTID:2180330482980756Subject:Fluid Machinery and Engineering
Abstract/Summary:PDF Full Text Request
Supercavitation is a magical physical phenomenon, when objects move underwater at a sufficiently high velocity, the surface will be surrounded by a layer of bubbles, which causes the resistance of objects reduced greatly in the water. Supercavitation has a broad application prospects of underwater drag reduction and defense weapons. With the emergence of a series of supercavitation technology achievements, supercavitation technology is gaining more and more attention around the world. However, underwater supercavitating flow is a complex issue involving many aspects of turbulence, multiphase flow, boundary layer and many more, with strong nonlinear and transient characteristics. There is no exact theory to describe it yet. At present, people use a large number of data obtained in experiments and the CFD numerical simulation to get the law of supercavitation formation, development and collapse. Based on the above background, in this paper, supercavity are studied by method of experimental research and numerical simulation.Using a set of horizontal supercavitation experimental device which was designed and developed by our own team, I do experiment research on the effect of different water depths, different aspect ratios, different surface structures, different surface materials of slender bodies on supercavity. I use high-speed photography to record process of supercavitating flow forming, development and collapse, Measure the displacement of slender bodies and the size of supercavity, calculate hydrodynamic parameters of velocity, cavitation number, drag coefficient, etc., analyze the effects of different conditions on Supercavity. The research results show that: With the increase of water depth, slender bodies’ moving stability will weaken, the drag coefficient increases, the size of supercavity decreases; with the increase of the aspect ratio of slender bodies, slender bodies’ moving stability will increase, the drag coefficient increases, the size of supercavity changes little; with the increase of surface grooves, slender bodies’ moving stability will weaken, the drag coefficient increases, the diameter of the supercavity will be reduced, the length will increase; with slender bodies coated with a hydrophobic material, slender bodies’ moving stability will weaken, the drag coefficient decreases, the size of supercavity changes little; when supercavity interact with the free surface, supercavity size becomes large, the duration will increase.By use of CFD numerical simulation software, simulate the three-dimensional unsteady supercavitation flow field at different water depths as well as with different aspect ratios and different surface structures of slender bodies. Consider the effect of different conditions on supercavity variation. Numerical simulation results and experimental results were compared consistent.
Keywords/Search Tags:supercavitation, high speed photography, numerical simulation, free surface
PDF Full Text Request
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