深海浮球内部气压对水下内爆波的抑制机理

Suppression and mechanism of underwater implosion waves by internal pressurization in deep-sea floating balls

深海潜器常携带中空浮球来为其提供浮力。陶瓷因其高强度、低密度等优点成为浮球的理想材料。然而,中空结构在外部高压环境下易发生内爆,产生的内爆波会对周围结构产生毁灭性损害。为了探索浮球内部初始气压对内爆波的影响,首先,利用气泡动力学对其不考虑球壳影响时进行理论分析,得到内爆波压力脉冲沿径向以指数-1衰减,并指出其物理意义和隐含假设,进而从能量分析得到增加内压使压缩空气消耗的能量增加,从而减弱释放到水中的压力波能量;其次,采用三相流固耦合有限元模型进行计算,考虑水的可压缩性和球壳因挤压引起的脆性破裂的影响,得到更为接近实际的内爆压力的分布。由于两侧挤压球壳,外部的水在不断扩大的缺口处产生向内的射流,造成内部气体非球形塌缩,后续压力波呈现出与球壳碎裂方式有关的方向性差异。通过有限元模型对内部初始气压的研究表明,增加初始内部气体压力到1 MPa时,压力脉冲在球壳表面处下降了15.6%~24.8%。这一结果表明,在几乎不增加浮球质量的条件下,增加内部初始气压具有很好地抑制近端内爆波强度的效果。

Deep-sea submersibles commonly employ floating balls to provide buoyancy,with ceramics being the preferred material due to their high strength and low density.However,hollow structures are susceptible to implosion under external high-pressure conditions,resulting in significant damage to surrounding structures.This study investigates the impact of initial gas pressure within the floating ball on the suppression of implosion pulses.Theoretical analysis using bubble dynamics examines the implosion pressure pulse at various initial pressures,revealing a decay along the radial direction with an exponent of-1.Energy analysis further demonstrates that increasing internal pressure enhances the compression of air,thereby reducing implosion energy.To obtain results closer to reality while considering water compressibility and shell fragmentation effects,a three-phase coupling finite element model is employed.The implosion of the spherical shell is initiated by squeezing on both sides,leading to non-spherical collapse of the internal gas caused by jet formation at the breach.Results indicate that the propagation of the pressure wave exhibits directional characteristics associated with the shell failure mode,with the level of directionality decreasing as the initial internal gas pressure increases.When the internal gas pressure is raised to 1 MPa,the pulse value of the pressure wave at the surface of the spherical shell decreases by 15.6%~24.8%.These findings suggest that increasing internal air pressure can effectively suppress implosion pulses without adding mass to the floating ball.