刚性球体三维高速垂直自由入水载荷

入水结构体在从空中弹道转入水下弹道的入水阶段，其周围的流体将呈现出强非线性性质，本文针对传统基于Wagner理论的结构体入水载荷计算模型不能很好描述流体三维流动的情况，基于无黏不可压流体流动模型，考虑流体弹性，采用微元边界运动等效方法对运动边界进行分段分析，计及入水过程中系统的动能损失，根据能量守恒，对刚性球体高速垂直自由入水过程中流体的三维流动进行了理论分析，建立了基于无黏不可压弹性流体的刚性球体垂直高速入水载荷计算模型，并与基于多介质任意拉格朗日欧拉方法的有限元模型进行了对比分析，验证了该方法的可行性。基于此模型，本文进一步分析了入水载荷的影响因素。该方法提供了一种计算结构体垂直高速入水载荷的思路，具有一定的理论意义和工程应用价值。

Three-dimensional vertical free high-speed water-entry impact of rigid sphere

At the initial stage of water entry, the water surrounding of the rigid sphere will show strong nonlinear characteristics. However, there are no exact three-dimensional effects in impact problem within the Wagner theory. Based on the non-viscous incompressible flow model, this paper considered fluid elasticity, used the micro boundary motion equivalent method to analyze the moving boundary, and based on the theory of energy conservation, which considered the loss of kinetic energy, analyzed the three-dimensional flow of the fluid around the rigid sphere during high-speed water-entry vertically, then established the analytical model which can calculate the water-entry impact of rigid sphere, and the analytical model is verified by an FEM model of multi-material ALE method. Base on the analytical model, this paper also analyzed the influencing factors of impact. The analytical model provides a fast algorithm for calculating the high-speed water-entry impact of structure, and has certain theoretical significance and engineering application value.