降落伞充气过程中伞衣外形及流场变化研究  

Study on the canopy shape and the flow field during parachute inflation process

作　　者：张红英[1] 刘卫华[1] 秦福德[1] 童明波[1] 

机构地区：[1]南京航空航天大学航空宇航学院,江苏南京210016

出　　处：《空气动力学学报》2011年第3期288-294,301,共8页Acta Aerodynamica Sinica

基　　金：国家自然科学基金(11002070);航空科学基金联合基金(2008ZC52037)

摘　　要：根据降落伞的结构和其在充气过程中的受力特性,以某平面圆形伞为原型,建立了伞衣充气过程中的计算流体力学与结构动力学耦合模型。并采用七孔探针对充满状态的绕流流场进行了定量测量,将该状态的试验结果和计算结果进行对比分析,二者的拓扑结构非常相似,压差系数也相差不大,因此所采用的数学模型是可靠的。在此基础上,对整个充气阶段的流场进行了数值模拟和分析,以详细了解降落伞整个开伞过程中伞衣外形变化及伞衣内外流场的变化情况。研究结果表明:①在初始充气阶段,伞衣展开部分外形基本保持较光滑的直筒形状,而非喇叭形。在主充气阶段:空气首先在伞衣顶部聚集,使伞衣顶部膨胀,然后膨胀部分向伞衣底边扩展,直到伞衣完全张满。②当伞顶孔被气流冲开后,伞衣的结构透气性对流场会产生显著影响。但从内外压力系数的变化来看,透气性对伞衣内滞止压力的影响较小,对伞衣外流场结构的影响较大,从而对伞衣外表面的压力影响较大。③对于此类有伞顶孔的平面圆形伞,当伞衣充气张开后,伞衣尾部出现气流分离,在一个漩涡区内形成两个相反旋转方向的漩涡。且随着伞衣直径扩张,分离区扩大,主流对漩涡区的剪切面积增大,因此漩涡区两个漩涡中外侧的一个漩涡增大,内侧漩涡被挤压至离伞顶更近的区域。According to the structure of the parachute and the force characteristics in inflation process,using a flat circular parachute as a prototype,the coupled model of computational fluid dynamics and structural dynamics is set up in the canopy inflation process.Quantitative measurement for flow field around has been carried out in the full state using seven-hole probe,and the test results and calculation results are analyzed comparatively,obtaining that the two topology structures are very similar,and the differential pressure coefficient also has an insignificant difference,so the mathematical model used is reliable.On this basis,the numerical simulation and analysis are carried out for the flow field in the whole inflation phase,in order to learn more about canopy shape changes and the flow field changes in internal and external canopy during the entire parachute opening process.The results show that：（1） In the initial inflation stage,canopy shape of expanded part remains relatively smooth and straight,rather than flared.In the main inflation stage,the air gathers at the top of the canopy at first,so that the top of canopy gets expanding,and then expansion part extends to the canopy bottom until totally full.（2） When the canopy vent is opened by airflow,structure porosity of canopy will have a significant impact on flow field.However,from pressure coefficient changes in internal and external canopy of view,porosity has less significant impact on the stagnation pressure within canopy but has more significant impact on the outflow of canopy structure,thus the pressure in outer surface of the canopy would be affected rather largely.（3） For such circular flat parachute with a vent,when the canopy inflated and opened,air separation appears in the canopy tail,then two vortexes forms at the opposite rotation directions in a vortex region.And,with the expansion of canopy diameter,the separation zone gets expanding,the shear zone area of the mainstream to the vortex region increases,so a lateral vortex of two

关 键 词：降落伞 充气过程 流场 数值模拟 

分 类 号：V244.216[航空宇航科学与技术—飞行器设计]