充气囊体材料撕裂及破裂后流场特性研究

通过实验的方法对囊体材料的撕裂特性和加强筋的止裂效果进行了初步的研究,并以飞艇为例利用数值模拟研究了囊体材料局部破裂后,破口处气体外泄的非定常流场结构及其演变过程.结果表明:囊体破裂后,裂纹快速扩展,通过合理地设计加强筋的强度和布局,并保证加强筋与囊体材料粘结牢固,可以起到良好的止裂效果;破口形成后,由于飞艇内外稀疏波和压缩波的作用,流场处于强烈的非定常状态,气体外泄的速度远小于裂纹的扩展速度,飞艇泻压所需时间和破口的尺寸有很大的关系,稀疏波在飞艇内的传播情况直接影响了泻压后内部压力的分布,稀疏波反射次数越多,压力分布越均匀.

An investigation on the tearing behavior of ballonet material and after-burst flow of an airship

The tearing behavior of ballonet material and the ability of reinforced tendon for preventing tear from propagating were experimentally studied,and the unsteady flow field around an after-burst airship was also numerically simulated.It was found that the tear propagation speed is much faster than the flow velocity.On the other hand,the reinforced tendons can prevent the tear from propagating effectively when they are stuck to the ballonet tightly with proper distribution.The computed flow field demonstrates strong unstationary leaking movement after the burst,which is accompanied by the rarefaction wave inside and compression wave outside the airship.The time for the pressured airship to fall down to balance the surrounding air depends strongly on the size of the tear.The propagation of the rarefaction wave influences directly the pressure distribution inside the airship.The more times the rarefaction wave reflects,the more uniformly the pressure distributes.