BALLISTIC WAVES IN HIGH-SPEED WATER ENTRY

• Published in: Journal of fluids and structures 1997-10, Vol.11 (7), p.819-844
• Main Authors: LEE, M., LONGORIA, R.G., WILSON, D.E.
• Format: Article
• Language: English
• Subjects: Compressible flows; shock and detonation phenomena; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Other topics in fluid dynamics; Physics; Shock-wave interactions and shock effects; Shock-wave interactions and shockeffects
• ISSN: 0889-9746; 1095-8622
• DOI: 10.1006/jfls.1997.0103

The generation and propagation of pressure waves (ballistic waves) by a body impacting and penetrating into water at high speed are investigated both analytically and numerically. An analytical model is, in principle, applicable for predicting ballistic waves by any projectiles of practical interest. The theory is general enough to handle oblique and/or multiple penetrations, and is valid for impacts at subsonic and supersonic velocities with respect to water. The ballistic waves radiated by a projectile are expressed as a convolution between the vertical component, which represents the response of a moving point source, and the horizontal component, which represents the response of the cross-section of the source. Diffraction effects resulting from the finite size are accounted for by including the horizontal pressure component. A time inversion phenomenon which can occur during supersonic penetration is also considered. The approach provides valuable insight into the pressure field generated by the penetration mechanisms. Numerical results are obtained by using a nonlinear wave-code, and these are in good agreement with the analytical predictions.