Experimental investigation on the longitudinal stability of the aerodynamically alleviated marine vehicle with multi-steps

Abstract

To investigate the hydrodynamic performance and motion characteristics of the ultra-high-speed aerodynamically alleviated marine vehicle (AAMV) with multi-steps, a towing tank test scheme was designed and carried out at the China Special Vehicle Research Institute. The study analyzed the effects of canard angle, flap angle, longitudinal center of gravity, and displacement tonnage on the motion stability of multi-stepped AAMV at different speeds. The results indicate that the canard generates an overturning moment that reduces the resistance but brings forward the speed at which porpoising behavior occurs. Additionally, the backward shift of the longitudinal center of gravity causes motion oscillation during the high-speed planing phase, which negatively affects longitudinal stability. On the other hand, the flaps provide aerodynamic lift and restoring moments, improving the lift-drag ratio and enhancing longitudinal stability. Furthermore, while increased mass may result in higher total resistance, it can actually improve resistance performance per unit mass and improve the lift-drag ratio at cruising speed. The computational fluid dynamics (CFD) method was used to analyze the destabilization mechanism of AAMV under extreme conditions in the test. Numerical results indicate that the longitudinal stability of AAMV is directly affected by the relative positions of the center of gravity and the center of pressure. These results demonstrate the changing rules of resistance performance and longitudinal stability of AAMV under different design parameters, thus providing a powerful tool for optimizing AAMV.