Research on Trailing Cavity of Underwater Vehicles Based on Potential Flow Theory

In the exceeding water process of underwater vehicles, the existing of trailing cavity will have distinct effects on the hydrodynamic characteristics of vehicles. Recent researches mostly leave gravity effect out of consideration, while the gravity will affect trailing cavity characteristics and then affect the hydrodynamic characteristics of vehicles. In this study, we research the effect of gravity on the trailing cavity of underwater vehicles. Firstly, a complex boundary model which taken partial cavity into consideration is established based on potential flow theory and a program according to this model is written. Because all flow parameter has nothing to do with the radial location, the research problem can be simplified as a two-dimensional problem and studied in polar coordinates. With regularization of the length of the navigation calculation model, infinity to flow velocity and the distance pressure, research domain can be represented by plane in the containing slit. The program is proved to be effective by comparison the results with the data in existing papers. Finally, we calculate the trailing cavity forms of a cone and an underwater vehicle under different cavitation numbers and Froude numbers to study the rules of trailing cavity forms changing with cavitation number and Froude number. Under the same number of Froude, the cavity size of the rear part of vehicle gradually decreases with the increasing cavitation number, and the maximum radius of the cavity equals to the biggest size of the tail radius of the vehicle. Under the same cavitation number bodies, vehicle trailing cavity length gradually increases with the increase of Froude number, but radius of the cavity of the vehicle changed little, the largest radius is equivalent to the tail radius of the vehicle.