Stern Hydrodynamic Characteristics Of Supercavitation Vehicle Research

Supercavitating vehicle is a kind of new hydrodynamic model of the underwater vehicle,which during the moving, except the head in the wet, the whole vehicle was covered by supercavitation which results in sailing resistance reducing from one or two orders of magnitude. It is one of the important directions for the future development of high-speed underwater weapons.As the vehicle is attached with supercavitation, the fluid dynamic characteristics and layout mode changes greatly, so the head cavitator and aft wetted surface become the main source of AUV motion control method. Many researchers studied hydrodynamic characteristics of head cavitator of supercavitation vehicle. Notably vehiclel wet tail control is also an important guarantee of the balances of forces and motion stability, and as the closure and collapse of the tail supercavitation influence to dynamic, tail surface control is realized as an effective measure of supercavitation dynamic design. The thesis comes from the research foundation, aimed that through replacing the traditional control of the tail rudder by expansion skirt, discuss its influencing to vehicle supercavitation flow pattern, compare the contribution of the tail structure and head cavitator to the dynamic characteristics and control layout,andprovide necessary data support for the supercavitation fluid dynamic characteristics based on the tail structure.The main research and conclusion of this study is:(1)Carried on an experiment in a water tunnel to study the typical triangle tail structure's supercavitation fluid dynamic characteristics(Chapter Two). Obtained the puncture cavity flow pattern characteristics and the fluid dynamic characteristics of tail surface, found that due to the effect of bubble tail closing and collapsing, there are some difficulties to maintain the stable tail puncture the morphology and control force.(2)Carried on an numerical computational study(CFD) of the supercavitation tail expansion skirt's fluid dynamic characteristics(Chapter Three). Based on multiphase flow CFD method, this paper analyses the numerical simulation method of natural cavitation.Based on the method analyzes the hydrodynamic properties of supercavitating vehicle.Within the scope of the 1° angle of attack, vehicle axial force, normal force and pitching moment are linear increased.There is a “stall” effect of axial force, normal force after the 1°,caused by the first cone wet decreases the tail of wet area. Because of increasing of wet surface before and after, the total torque remain unchanged between 1.5~3°.(3)Carried on an experiment in a water tunnel to study series of tail structures' supercavitation fluid dynamic characteristics(Chapter Four). Designed water tunnel experimental model, builded a ventilation and test platform. Studied the expansion skirt ventilation cavitation characteristics through manual ventilation. The results shows that, the drag coefficient, lift coefficient derivative and moment coefficient derivative of tail increases with the expansion of the half angle and expansion of bottom diameter, which performs well with the numerical calculation results.The results of the study, provided powerful support to further study of the head cavitator,tail skirt control surface and thrust vector with the hydrodynamic layout design.