Study On The Theoretical Model Of Hypervelocity Fluid Penetration Of Long-rod Projectile

Long rods are expected to experience higher impact velocities in the future as a result of the further development of new launching systems and ultra-high-energetic materials.It is therefore of considerable importance to investigate the compressible fluid theory of long-rod hypervelocity penetration.By combining theoretical analyses and numerical simulations,this thesis mainly carries out the following research:Firstly,based on the compressible fluid theory and the quasi-steady penetration assumption,an integrated approximate compressible fluid model of long-rod hypervelocity penetration that ignores the influence of shockwaves is established in this thesis to solve the long-rod projectile hypervelocity penetration.By comparing the solutions of this theoretical model with the Alekseevskii-Tate model(Alekseevskii(1966),Tate(1967,1969)),experimental data,and numerical simulations,the validity of the model is verified.Subsequently,a dynamic compressible hydrodynamic limit is presented after further analyzing the similarities and differences between our theoretical model,the Alekseevskii-Tate model,and the hydrodynamic theory.Based on analyses of different projectile–target combinations,the influence of the compressibility of projectile/target materials on the penetration efficiency and the application ranges is discussed,and the proposed theoretical model is deemed appropriate for velocities from 1.5 km/s to 12 km/s.Meanwhile,analyses show that when the compressibilities of both the projectile and target materials are similar and relatively low,the traditional Alekseevskii-Tate model for long-rod high-speed penetration can be appropriately extended to hypervelocity penetration.Finally,the numerical simulations of three projectile-target combinations at different velocities are carried out.By combining with the comparison between the proposed theoretical model and the Alekseevskii-Tate model,the influence law of the compressibility on hypervelocity penetration process is studied.The analyses show that when the compressibilities of projectile and target are different,the influence of material compressibility on the penetration process parameters is mainly reflected in the penetration velocity and the penetration time,and the influence increases with increasing striking velocity.In addition,the compressibility improves the penetration ability of the projectile and enhances the penetration resistance of the target.Moreover,compared with the target,the influence of the compressibility on the projectile is more significant.The large compressibility of the target has a great influence on the penetration time,while the large compressibility of the projectile has a great influence on the penetration velocity.