An approximate compressible fluid model of long-rod hypervelocity penetration

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. 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 study. 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, we present a compressible hydrodynamic limit after further analyzing the similarities and differences between our model, the Alekseevskii-Tate model, and the hydrodynamic theory. Finally, based on analyses of different projectile–target combinations, the influence of the compressibility of projectile/target materials on the penetration efficiency is discussed. Meanwhile, the proposed model is deemed appropriate for velocities from 1.5 km/s to 12 km/s. In addition, under the conditions that either the projectile and target are similar or both are weakly compressible, we demonstrate that the applicable velocity range of the Alekseevskii-Tate model can be appropriately extended.