滑移动网格在波浪水面迫降数值模拟中的应用

Application of sliding dynamic grid to wavy water ditching simulation

为研究飞机在波浪中迫降时不同航向对迫降性能的影响,在刚性动网格和滑移网格方法的基础上,开发出将两者相结合的滑移动网格方法,在保证自由面处于网格加密区的同时,可以模拟飞机在复杂海况下的任意姿态.数值模拟三维平板斜向冲击入水,将数值模拟的垂向运动历程及表面压强分布与实验数据进行对比分析,验证数值方法的有效性并得到网格参数的设置经验;用滑移动网格方法对飞机平静水面迫降进行数值模拟,将数值模拟的运动历程与实验数据进行对比,验证滑移动网格方法的有效性;在应用数值造波的基础上,模拟研究飞机迎浪、顺浪和平行于波浪3种不同航向的迫降,对比分析3种工况下飞机的运动历程和各部件受力情况.模拟结果表明:波浪中迫降的最优航向是平行于波浪,其垂向冲击力峰值比平静水面迫降大12%,滚转和偏航运动造成的影响也较小;迎浪迫降会产生较大的俯仰角峰值,垂向冲击力峰值比平静水面迫降大149%,并且会遭受多次波浪冲击作用,是最危险的迫降航向.

To study the effect of different courses of ditching on wavy water,a sliding dynamic grid method based on rigid dynamic grid and sliding grid is developed.While ensuring that the free surface is in the grid encryption area,it is possible to simulate any attitude of the airplane under complicated sea conditions.By simulating three-dimensional rectangular flat plate oblique impact into water,the vertical movement history and the pressure distribution are compared with experimental data to verify the effectiveness of numerical method,and the grid parameter setting experience is also got.The simulation results of airplane ditching on calm water using sliding dynamic grid method are compared with experimental data to verify the effectiveness of sliding dynamic grid method.On the basis of application of wave making method,numerical simulation of three different ditching courses on wavy water,such as heading waves,following waves and parallel to waves are made.By comparing and analyzing the movement history and the force of different parts,it is concluded that the optimal course of ditching on wavy water is parallel to waves,the vertical impact peak is 12%larger than that on calm water,and the effects of roll and yaw motion is small.The most dangerous situation is heading waves,which will produce larger pitch angle,the vertical impact peak is 149%larger than that of calm water ditching,and will suffer many wave impacts.