薄壁金属气囊抛撒性能流固耦合分析

Analysis of the dispersing performance of a thin-walled metal gasbag based on fluid-structure interaction method

为研究机载布撒器囊式抛撒系统中气囊的抛撒性能,以初始为扁平结构的薄壁金属(304不锈钢)气囊为研究对象,采用流固耦合的方法对其膨胀抛弹过程展开数值仿真分析,得到囊内的流场特性和囊壁的应力响应,计算结果与试验吻合较好.分析了入口边界条件及气囊结构对抛撒结果的影响,计算结果表明:气囊入口直径和入口边界条件是影响子弹分离速度和过载的关键因素,装药量、入口直径越大,子弹过载越大;一定装药量下,气囊入口直径不同时,子弹存在极限分离速度;气囊初始面积对子弹分离速度影响很小(仅4%),主要影响囊内的燃气压力,初始面积越大囊压越小,有利于降低囊壁的应力值.计算结果可为气囊结构的优化设计与工程实际应用提供重要参考.

To research the performance of gasbag used in bladder-type dispersal system, the fluid-structure interaction（FSI） model is established to simulate the inflating process of the metal gasbag（304 stainless steel）with a initially flat form. Then the dynamic response of bag＇s deformation and the changing law of internal flow field are acquired,and the results show a good agreement with the experimental results. Besides,the performances of gasbag with the change of its geometry and inlet conditions are investigated. The results show that the inlet diameter of gasbag and the inlet conditions are the key factor influencing the bullet＇s separating speed and overload. The larger the inlet diameter or the charge weight is,the greater the bullet＇s overload is. And when the bag＇s inlet diameter is different,there is an existence of the extreme separation speed of bullet with a certain amount of charge.The bag＇s initial area has a small impact on the change of speed（the difference is only 4%）,while it affects the magnitude of the pressure of gas in the gasbag obviously. The larger the area,the smaller the pressure presents,which is beneficial to reducing the stress level of the wall of gasbag. So the calculation results can provide a mainly reference for the optimal design and engineering application of gasbag.