基于改进Wagner方法的轴对称体入水“后时段”砰击载荷数值计算

文章基于三维边界元方法研究了三维轴对称体入水砰击载荷的数值算法。算法从三维力学模型出发,继承Wagner自由液面抬升理论,引入浸深因子Cw以确定自由液面抬升高度,将自由液面线性化处理,同时考虑网格运动,在自由液面附近对网格进行截断重构,以确保水下湿面积的精准。算法中使用考虑加权运动项的非线性伯努利方程计算得到入水结构的表面压力,进一步积分可得入水结构的总体受力;另外,算法中引入虚拟面元的概念,将砰击载荷计算时历延长至液面高于坠物制高点之后,扩大了传统入水载荷计算的时历范围,并且文中引用Alaoui半球入水试验,对算法的正确性及适用性进行了验证。

Numerical calculation of the slamming load for axisymmetric geometries during the later entry time based on generalized Wagner theory

A numerical code used for calculating the slamming load for axisymmetric geometries based on 3D BEM was mainly introduced. The 3D mechanical model and Wagner’s theory which considering the u-plift free surface were both used in the numerical code. Cw which was called wetting factor was introduced to ensure the exact height of the uplift free surface. At the same time, the grid’s movement was also con-sidered and along the interface between the geometry and the free surface one group of grids were modified for a precise wet area. The Nonlinear Bernoulli equation considering the grid’s movement was used for cal-culating the hydrodynamic pressure and the force could be obtained through integration. Besides, the con-ception of Virtual surface element was brought here so that the slamming load when the top point of the falling object was under the free surface could be achieved. That is to say, the traditional calculated time process was extended. At the same time, Alaoui slamming test was used to test the code’s validity.