Numerical simulation study on hydrodynamic time-delay characteristics of supercavitating vehicle

Abstract

Due to the existence of the time-delay effect of the supercavity, the fluid dynamics of the supercavitating vehicle in the maneuvering will exhibit extremely strong unsteady characteristics, which will bring great challenges to the hydrodynamic acquisition, motion performance analysis and control scheme design and evaluation of the vehicle. Therefore, it is of great significance to study the hydrodynamic characteristics and formation mechanism of the vehicle in supercavitating state. In this paper, a three-dimensional numerical model for continuous motion of the supercavitating vehicle at varying angles of attack is established by using the dynamic mesh technique. The accuracy of the model is verified by using the water tunnel test results. Through simulation, the unsteady cavitation development and hydrodynamic characteristics of the supercavitating vehicle at different speeds, swing frequencies and preset rudder angles are obtained. The results show that the hydrodynamics of the supercavitating vehicle under unsteady motion has time-delay characteristics, and the prediction results of the conventional hydrodynamic calculation method of the vehicle have large errors. The cavitation time-delay effect and the dynamic development of the attached cavitation are the fundamental reasons for the formation of the unsteady hydrodynamic time-delay characteristics of the supercavitating vehicle. The hydrodynamic time-delay characteristics of the supercavitating vehicle is significantly enhanced with the increasing of velocity and weakened with the increasing of swing frequency. The preset rudder angle of the cavitator results in different time-delay characteristics when the vehicle swings at positive and negative angles of attack.