飞行人员单人漂浮装置漂浮姿态及其稳定性研究

Floating attitude and floating stability of individual flotation device for aircrews

目的研究某型飞行人员单人漂浮装置在强风浪海况下的漂浮姿态及漂浮稳定性,指导结构优化。方法构建基于重叠网格的多自由度运动仿真计算方法,在非定常雷诺平均Navier-Stokes方程基础之上引入流体体积(volume of fluid,VOF)多相流模型和湍流模型,对漂浮装置进行结构简化建模,模拟并分析5级海况上限条件下波浪周期内漂浮装置的运动姿态。结果在自由漂浮状态下,装置主要受到横浪的影响而发生侧向倾覆;通过船底下沉式设计、在两侧浮筒下方中心位置增加平衡水袋以及在浮筒外侧增加辅助气囊可以有效提高装置在横浪冲击下抗侧倾的能力,且装置绕垂直轴发生的偏摆角度随水袋数量增加而减小,辅助气囊尺寸的增加也可进一步抑制装置侧向倾覆的角度。结论利用计算流体动力学(computational fluid dynamic,CFD)数值仿真模拟法研究漂浮装置漂浮姿态及稳定性具有可行性,提升装置载人后重心与浮心空间位置的一致性、增加装置绕垂直轴的转动惯量、增大装置产生侧倾趋势后的恢复力矩以及增加其抗倾覆力矩,可有效提升漂浮装置整体漂浮稳定性。

Objective To investigate the floating attitude and floating stability of an individual flotation device in stormy sea environments,and to provide data for structure optimization.Methods A multi-degree-of-freedom motion simulation calculation method was established to analyze the moving posture of the flotation device under the upper limit of class 5 sea state based on overlapping grids.The calculation was based on the unsteady Reynolds-Averaged Navier-Stokes equations,and the VOF multi-phase flow model and turbulence model were introduced.Results In the freefloating state,the device was mainly affected by transverse waves and capsized laterally.The sunken bottom,additional balancing water bags at the bottom edge and additional air bags attached to the flotation device could effectively improve the anti-roll ability of the device under the impact of transverse waves.Moreover,the angle of deflection decreased with the increase of water bags,and a larger size of the additional air bags could do more to restrain the side overturn angle of the device.Conclusion CFD numerical simulation can be used feasibly to study the floating attitude and stability of the flotation device.The overall flotation stability of the device can be effectively improved by reducing height difference of the center of gravity and the center of buoyancy after manned operation,increasing rotational inertia of the device around the vertical axis,increasing the recovery moment while the device's overturning tendency occurs and by increasing its antioverturning moment.