Numerical simulation and analysis of the underwater implosion of spherical hollow ceramic pressure hulls in 110 0 0 m depth

Pressure hulls play an important role in deep-sea underwater vehicles. However, in the ultra-high pres -sure environment, a highly destructive phenomenon could occur to them which is called implosion. To study the characteristics of the flow field of the underwater implosion of hollow ceramic pressure hulls, the compressible multiphase flow theory, direct numerical simulation, and adaptive mesh refinement are used to numerically simulate the underwater implosion of a single ceramic pressure hull and multiple linearly arranged ceramic pressure hulls. Firstly, the feasibility of the numerical simulation method is verified. Then, the results of the flow field of the underwater implosion of hollow ceramic pressure hulls in 110 0 0 m depth is analyzed. There are the compression-rebound processes of the internal air cavity in the implosion. In the rebound stage, a shock wave that is several times the ambient pressure is gener-ated outside the pressure hull, and the propagation speed is close to the speed of sound. The pressure peak of the shock wave has a negative exponential power function relationship with the distance to the center of the sphere. Finally, it is found that the obvious superimposed effect between spheres exists in the chain-reaction implosion which enhances the implosion shock wave.(c) 2022 Shanghai Jiaotong University. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )

Automated summary

Pressure hulls are crucial for deep-sea underwater vehicles, but they are susceptible to implosion, a highly destructive phenomenon in ultra-high pressure environments. In this study, compressible multiphase flow theory, direct numerical simulation, and adaptive mesh refinement were employed to simulate the underwater implosion of single and multiple ceramic pressure hulls. The feasibility of the simulation method was verified, and the flow field characteristics of hollow ceramic pressure hulls at a depth of 1100 meters were analyzed. The implosion process involved compression-rebound of the internal air cavity, generating a shock wave with a pressure peak several times higher than ambient pressure. The shock wave's pressure exhibited a negative exponential relationship with the distance from the center of the sphere. Additionally, a chain-reaction implosion revealed a superimposed effect between the spheres, enhancing the implosion shock wave.