CFD Study on Penetration of Sonic Boom Applying a Wavy-Water Model

The penetration of sonic booms into the ocean and an estimation of the extent of their in fl uence are important topics for supersonic and hypersonic aviation. Most prior studies were conducted assuming a fl at-water surface. However, it is known that the e ff ect of the surface waviness is not negligible in the case of real ocean environments. In the present study, the numerical method analyzes the two-dimensional fl ow fi eld of sonic boom propagation across the air and water is proposed. When the fl ight Mach number of an aircraft is higher than 4.4, the underwater fl ow fi eld becomes supersonic, and a sonic boom is generated there. The numerical results show that, in the underwater subsonic regime, the penetrating waves have the form of evanescent waves under either fl at or wavy water surface, but the waviness-induced ripples with the smaller decay rate are responsible for deeper penetration. In contrast, in the supersonic underwater fl ow, the surface waviness hardly a ff ects the penetration depth of underwater sonic booms, although it can slightly weaken the boom intensity. The e ff ect of the amplitude of surface waviness on the underwater penetrating wave was also investigated. :