Numerical Simulation On Water Entry Process Of Supercavitating Vehicle

Underwater supercavitating vehicle weapons can achieve long-range penetration,precise strike,and efficient damage,and have high research value.In practical applications,it is required to have the ability to launch above water surface.After the process of entering the water across the medium,it can hit underwater or surface targets,which involves the problem of the vehicle entering the water across the medium and the problem of underwater attitude deviation.At the same time,it also needs to have good cavitation morphology and low velocity loss,so artificial ventilation devices are usually used to provide active ventilation,which also involves the problem of artificial ventilation supercavitation.In this paper,the finite volume based numerical simulation method is used to study the water entry process of supercavitating vehicle through the coupling of transient multiphase flow field and rigid body multi degree of freedom motion dynamics and kinematics equations.The main research contents are as follows:A finite volume method was used to establish a water entry model for the vehicle,and the numerical simulation results were compared with theoretical and experimental results from two aspects of cavitation and water entry motion to verify the accuracy of the numerical method.The appropriate calculation parameters were determined through comparative calculations of different grid numbers and time step sizes.The water entry process of the vehicle without artificial ventilation and cavitator inclination angle is analyzed from the aspects of multiphase flow field,pressure distribution,force and movement,etc.According to the cavitation shape,the water entry process is divided into four stages: air flight,cone water entry,column water entry,and full water entry.The results show that the cavitation undergoes significant unsteady changes during the water entry process,and the force and motion of the vehicle are highly correlated with the changes in wetting force.The influence of artificial ventilation and cavitator inclination angle on the process of entering water and underwater navigation was studied by giving them respectively.The results show that the inclination angle of the cavitator can change the relative position of the vehicle and the bubble by providing a head up torque,thereby changing the distribution of wet areas and forces,and achieving attitude flattening;Artificial ventilation can significantly improve bubble morphology,reduce load,and reduce velocity loss.The joint effect of two parameters on the water entry process was studied by simultaneously giving different artificial ventilation flow rates and cavitator inclination angle.As the inclination angle of the cavitator increases and the ventilation flow rate decreases,there is an overall trend of increasing force,increasing speed loss,and accelerating leveling speed,and there is a phenomenon of mutual reinforcement between the two parameters: the larger the inclination angle of the cavitator,the stronger the impact of ventilation flow rate;The smaller the ventilation flow rate,the stronger the influence of the inclination angle of the cavitator.When the ventilation flow rate is large and small,there are two different flattening modes for the vehicle: the increasing angular velocity flattening mode and the periodic pitch flattening mode.The water entry flattening motion in different modes exhibits different characteristics.Finally,by giving the rotation rate of the cavitator,the water entry flattening motion was achieved under variable cavitator conditions,and the influence of the cavitator rotation rate on the water entry process was analyzed,and the rotation rate conditions that can achieve water entry flattening in the corresponding time were obtained.