基于CFD方法的十字形降落伞–航行体系统数值分析

Numerical Analysis of 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，得到了详细的流场计算结果。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%。结果显示十字形降落伞–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 flow field and drag performance of the cross parachute，the PISO algorithm is used to conduct numerical calculations of the unsteady flow around the cross parachute-vehicle system based on Realizable k-ε model，and detailed flow field calculation results are obtained. Flow field distribution rules of the cross parachute-vehicle system and changes in aerodynamic characteristics of the parachute and the vehicle under different trailing distances are studied. The results show that when towing ratio λ is no larger than 2，the vehicle and the parachute form a closed flow，and drag loss of the parachute is serious. When towing ratio λ is larger than 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，and the flow form gradually changes from closed to open. When trailing distance λ changes from the minimum to the maximum， the pressure difference Δp increases by 12%. Resistance of the parachute is restored and resistance fluctuation is reduced. When towing ratio λ is 4，resistance of the parachute and the vehicle increases by 1.8% and 25% respectively. Velocity and pressure contours 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.