SIMPLIFIED DYNAMICAL SYSTEMS ANALYSIS OF SUPERCAVITATING HIGH-SPEED BODIES

Supercavitating bodies can achieve very high speeds under water by virtue of reduced drag: with proper design, a cavitation bubble is generated at the nose and skin friction drag is drastically reduced. Depending on the type of supercavitating vehicle under consideration, the overall drag coefficient can be an order of magnitude less than that of a fully-wetted vehicle. However, control and maneuvering present special challenges. This article presents a simplified dynamical systems model that captures what may be considered the key features of the system: namely forces curves that are nearly slope-discontinuous as the vehicle afterbody impacts the cavity boundary, and a time delay associated with the advection of cavity disturbances downstream from the cavitator to the point of afterbody impact. The model is then employed to map the stability of the system as key design parameters are varied, and to investigate the behavior of the system under various conditions.