基于CFD方法的十字形降落伞-航行体系统数值分析

Numerical analysis of the cross parachute- vehicle system based on CFD method

摘要:

为研究航行体对十字形降落伞流场和阻力性能的影响，基于Realizable k-ε模型采用PISO算法开展了十字形降落伞-航行体系统的非定常绕流数值计算，获得了精细的流场情况。研究了不同拖曳比下十字形降落伞-航行体系统的流场分布规律与降落伞衣及航行体的气动特性变化，结果表明：当拖曳比λ≤2时，航行体和降落伞衣形成闭式流动，降落伞衣阻力损失严重，当拖曳比λ>2时，航行体尾流区的压力恢复，降落伞衣底部形成稳定的正压区，流动形式由闭式转化为开式，拖曳比λ最大时的压差Δp相较拖曳比最小时的压差增加12%。降落伞衣阻力恢复，阻力波动减小，当拖曳比λ=4时，降落伞与航行体的阻力分别增加1.8%，25%。速度与压力云图显示十字形降落伞-航行体系统的流场和压力分布更为对称，且气动特性处于最佳状态。

Abstract:

In order to study the impact of the vehicle on the flow field and drag permeance of the cross parachute, the PISO algorithm was used to conduct numerical calculations of the unsteady flow around the cross parachute- vehicle system based on the Realizable k-ε model, and a detailed flow field was obtained. The flow field distribution rules of the cross parachute-vehicle system and the changes in aerodynamic characteristics of the parachute and the vehicle under different trailing distance were studied. The results show that when the trailing distance λ≤2, the vehicle and the parachute form a closed flow. The drag loss of the parachute is serious, and when the trailing distance λ>2, the pressure in the wake area of the underwater vehicle recovers, a stable positive pressure area is formed at the bottom of the parachute, the flow form gradually changes from closed to open. The pressure difference Δp when the trailing distance λ is the largest increases by 12% compared to the pressure difference when the trailing distance is the smallest. The resistance of the parachute is restored and the resistance fluctuation is reduced. When the drag ratio λ=4, the resistance of the parachute and the vehicle increases by 1.8% and 25% respectively. The velocity and pressure contour show that the flow field and pressure distribution of the cross parachute-vehicle system are more symmetrical and the aerodynamic characteristics are in the best state.