Nonlinear Vibration and Control of Underwater Supercavitating Vehicles

Abstract

When a supercavitating vehicle navigates underwater at a high speed, most of the surface is wrapped by cavity. With the influences of the system parameters and launching state, the nonlinear oscillation of the vehicle always occurs because of the collision between tail and cavity. To solve the problem, a fin deflection control method is proposed based on a 4-D dynamic model of the supercavitating vehicle. The nonlinear dynamic characteristics of the supercavitating vehicle are researched by using dynamic map. And some conventional approaches of dynamics analysis are used to further study the vibration characteristics of supercavitating vehicles with variable control parameters of fin deflection angle and initial conditions. The results indicate that the supercavitating vehicle model differs from a common dynamics system because, apart from control parameters, its vibration characteristics are also associated with initial conditions of the system, which induce some novel nonlinear phenomena, such as transient oscillation and vibration state transition. The control parameters can be set according to the dynamic map, and the fin deflection control method can effectively suppress the nonlinear vibration of the vehicle. The research results have theoretical guidance and engineering significance for the stability control of supercavitating vehicles.

Keywords

• Supercavitation
• control parameter
• nonlinear dynamics
• initial condition