小型降落伞充气和伞衣塌陷过程

Process of inflating and canopy collapsing for small parachute

为了研究小型电子装置降落伞伞衣在充气和塌陷过程中的流场特性,判断伞衣充气过程的安全性,采用任意拉格朗日-欧拉(Arbitrary Lagrange Euler,ALE)方法,对伞衣的分离剪切层演化及其尾流区的涡运动进行分析,探讨来流速度和前置体质量等因素对充气过程的影响.结果表明:根据流场演化的特点,降落伞充气过程中尾流再附现象导致伞顶塌陷.在物伞系统速度比为5~20,质量比为0.5~1.4等大范围工况内,伞衣只存在局部塌陷,开伞失败的风险较小,是较为安全的工况;当前置体质量过小时,伞衣可能发生大面积塌陷,是较为危险的工况.

In the process of parachute inflating,the coupling of flexible canopy and fluid produces a large deformation,including complex flow phenomenon. In this paper,for the small electronic device parachute,the characteristics of the flow field in the process of inflating and collapsing of the canopy are studied,and the safety of the inflation of the canopy is analyzed. By Arbitrary Lagrange Euler(ALE)method,the evolution of the separation shear layer of the canopy and the vortex motion of its wake are analyzed,and the effects of factors such as the flow velocity and the forebody weight on the inflation are given. The results show that according to the characteristics of the evolution of the flow field,the wake re-contact phenomenon of the parachute leads to the collapse of the canopy. For parachute system,in the speed ratio of 5 to 20,the mass ratio of 0.5 to 1.4,the canopy only exists local collapse,the risk of failure of opening the parachute is small,these are relatively safe working conditions. When the forebody weight is too small,the canopy may collapse in large areas,it is more dangerous working conditions.