基于边界元法的三维结构体滑跳运动数值仿真

利用滑跳运动实现近水面高速机动飞行的击水式飞行器是近年来的热点问题，三维结构体高速斜入水冲击载荷求解是滑跳运动数值仿真的关键步骤。针对滑跳运动开展研究，建立了一种基于边界元法的可以考虑结构弹性效应的三维结构体近水面滑跳运动时域数值仿真方法。高速斜入水冲击载荷由边界元法求得，利用状态方程直接积分法求解得到结构节点位移动力响应，并通过滑跳运动动力学模型更新结构体的质心位置及运动速度。针对钢球高速斜入水冲击现象进行数值仿真并与试验结果对比，验证了所提方法的准确性。开展三维刚性球冠体的近水面滑跳运动时域数值仿真和变参分析，得到了结构质量、初始高度、水平抛出速度和半径大小4种参数对球冠体滑跳运动的影响规律。考虑结构弹性效应后，高速斜入水冲击载荷减小，对球冠体滑跳运动也有一定影响。 

Numerical simulation of skipping motion of three-dimensional structure based on boundary element method

In recent years, the water striking aircraft which realizes high-speed maneuvering flight near the water surface by using skipping motion has become one of the hot issues in research, and the solution of high-speed oblique water impact load of three-dimensional structure is the key step of skipping motion numerical simulation. Based on the boundary element method, a time-domain numerical simulation method of water surface skipping of three-dimensional structure considering structural elastic effect is established. The high-speed oblique water impact load is obtained by the boundary element method, and the displacement dynamic response of the structural node is obtained by the direct integration method of the state equation. Moreover, the centroid position and motion speed of the structure are updated by the skipping motion dynamic model. To verify the accuracy of the fluid load solution algorithm of this method, the numerical simulation of high-speed oblique water impact of steel sphere is carried out and compared with the experimental value. The time-domain numerical simulation and variable parameter analysis of skipping motion of three-dimensional rigid spherical crown are carried out. Then, the effects of structural mass, initial height, horizontal throw speed and radius on the skipping motion of the spherical crown are obtained. After considering the elastic effect, the impact load of high-speed oblique water entry decreases, which also has a certain influence on the sliding and jumping motion of the spherical crown.