Papers by Keyword: Supercavity

Abstract: This paper based on the Homogeneous equilibrium multiphase flow theory.By using FLUENT software the high-speed underwater projectile resistance characteristics were studied.Analyzed the influence of cavitator diameter and Cavitation number on drag reduction characteristics of the projectile,and compared with the empirical formula.The results showed that the larger the diameter of cavitation,the easier supercavitation natural formation,but the drag coefficient be greater.

Abstract: One stage light gas gun is an important device for experiments of low-speed supercavitation projectiles. After a reasonable simplification to the gas gun, movements of the projectile in the barrel have been analyzed and the relationships between the initial pressure of the gas gun and the exit velocity of the projectile were obtained. For meeting the velocity difference between at the gun exit and water-entry, a speed impairment factor was employed. The results of the adiabatic analysis of the simplified gun show that the best ratio between gun chamber volume and the barrel length is related to the gas thermodynamic process and the gas residual pressure has relation to the gas thermodynamic process. The low-speed supercavitation projectile experiments have been carried out. The movements of the projectile in the gas gun and the supercavitation shape and projectile speed after water-entry have been numerically simulated.

Abstract: Owing to the existence of supercavition affect the trajectory as well as the stability of motion of projectile. So modeling and controle problems for supercavitation prjectile are complicated and important. The paper analysed the hydrodynamic of supercavitation projectile. And the nonlinear dynamics equatioons motion in body coordinates were obtained. Inorder to obtain the excellent stability performances of projectile, the robust pole assignment method was used to controle the attack angle of head(cavitator). And the attack angle of head effect to the stability of supercavitation projectile was obtained based on stability equtaions. Several structure parameters of the cavitator were designed to compared the contrlole efficiency. Simulation results show that projectile can have good navigation stability through controle the cavitator attack angle. The controle method is of engineering signification.

Abstract: A finite volume method has been formulated based on the ideal compressible potential theory. By using the continuity equation and Tait state equation as well as Riabouchinsky closure model, an "inverse problem" solution has been presented for the supercavitating flow. According to the impenetrable condition on the surface of supercavity, a new iterative method for the supercavity shape has been designed to deal with the effect of compressibility on supercavity shape and pressure field. The supercavity shape changes from ellipse to taper, as well as the drag coefficient increases with Mach number increasing. The results compare well with the experiment data and empirical formula, and the numerical method is proven to be valid.