On water-entry cavity evolution models and maneuvering motion of supercavitating vehicle

The maneuverability of supercavitating vehicles is significantly affected by disturbance from their control surfaces during the water-entry process. In this paper, experiments and simulations on cavity evolution models and vehicle dynamic characteristics are carried out to investigate the influence of the water-entry disturbance on the water-entry maneuvering motion process of supercavitating vehicles. In the water-entry experiment of medium speed projectiles based on the high speed photography, the shapes of cavity contours are extracted and the applicability of the cavity evolution models to the problem of water-entry maneuvering motion is verified. A kind of more correct prediction model of cavity shape is chosen by the comparison. A mathematical model on the water-entry maneuvering motions of vehicles is developed based upon certain simplifications, which makes an improvement on the three-dimensional cavity topology algorithm. Afterward, the simulations on the water-entry maneuvering motion of the vehicle are carried out, from which the real-time interaction between the vehicle and the cavity is extracted and the influence law of the fin deflection angle on the vehicle dynamic characteristics is analyzed. The influence mechanism of the desynchronization of fins' contacting water on the water-entry maneuvering motions of vehicles is revealed. It is found that the fin deflection angle of 10° is the most conducive to enhancing the vehicles' ability to stabilize their attitudes during water-entry maneuver by analyzing the fin efficiency and planning parameters.