轴对称降落伞稳定下降阶段的流场特性

文章根据降落伞的特点,通过3点假设(伞衣的薄膜假设、降落伞的轴对称假设和流场的定常 假设),将三维复杂流动问题,转化成二维轴对称问题,以节约计算时间。然后,建立轴对称降落伞的流体力 学计算模型,利用数值模拟手段,求解RNG(Renormalization Group)k-epsilon湍流模型下的N—S方程组,获 得与有关单位试验相吻合的计算结果。分析发现带顶孔的轴对称降落伞绕流和亚临界状态下带中心孔的 圆球绕流,在尾流区拓扑结构上几乎完全一致。结果表明建立的轴对称降落伞模型,能够揭示降落伞流场 的本质特性,为进一步研究降落伞流场的流动机理和流固耦合问题打下基础。

The Flowfield Characteristics of an Axisymmetric Parachute in Terminal Descent

According to the characteristics of parachute, based on three assumptions (membrane assumption of canopy, axisymmetric assumption of parachute, and steady assumption of flowfield) , the 3-D complex flow problem was first transformed into an axisymmetric problem with computational timesaving. And then a fluid dynamics computational model was established. By solving RNG (Renormalization Group) k- epsilon turbulence N - S Equations, the numerical simulation result is in good agreement with the relative experiments. It is found that the wake topological structure of an axisymmetric parachute with top vent is almost the same as that of a sphere with center vent under subcritical flow condition . The results also indicate that the axisymmertric parachute model here can be used to explore the basic characteristics of parachute flowfield. At the same time, the established method here may lay foundation for further investigating parachute flow mechanism and fluid - structure coupling.