tailieunhanh - Study on the spatial motion model of underwater projectile

This paper studies the three-dimensional motion modeling for a super cavitating projectile. 6-degrees of freedom equation of the motion was constructed by defining the forces and moments acting on the supercavitating body while moving underwater. | Research STUDY ON THE SPATIAL MOTION MODEL OF UNDERWATER PROJECTILE Nguyen Huu Thang Nguyen Hai Minh Dao Van Doan Abstract This paper studies the three-dimensional motion modeling for a super cavitating projectile. 6-degrees of freedom equation of the motion was constructed by defining the forces and moments acting on the supercavitating body while moving underwater. The impact force of the projectile tail with the cavity wall is determined by the super-cavity size calculations when considering the effect of the reduction of the super-cavity size. The calculation results obtained the integrated motion of the super cavitating projectile in the water environment which was the basis for the study of scattering for the underwater projectile. Keywords Underwater projectile Super-cavity Supercavitating projectile Planing force Cavity model. 1. INTRODUCTION In literature the dynamics of a supercavitating body is more complex than that of moving body in a flow regime that does not separate in the air or in water. The complexity causes are the cavity instability surrounding the body and the discrete impact between the body tail and the cavity wall. At each moment the force is determined from the relative position and relative motion of the body compared with the cavity and the cavity shape formed in the first time. Experimental studies in 6 have shown that the stability of motion of supercavitating body can be achieved with all velocities ranging from 50-1450 m s . The analysis showed that the four different mechanisms of motion stabilization sequentially act at motion velocity increase . b a Figure 1. Schemes of motion of supercavitating models. Two - cavity flow scheme V 50 m s In this case the hydrodynamic drag center is placed behind the mass center and stabilizing moment of the force Y2 acts to the model. It means that the classic condition of stability is fulfilled. Sliding along the internal surface of the cavity Fig. 1b V 70-200 m s To compensate the .