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返回舱高雷诺数再入过程底部流动稳定性

BASE FLOW STABILITY OF RETURN CAPSULE DURING REENTRY PROCESS WITH HIGH REYNOLDS NUMBER

  • 摘要: 返回舱高雷诺数再入过程中存在肩部高热流、底部阻力无法准确预测以及非定常振动等问题,解决此类问题的关键是分离和转捩等物理现象的准确识别. 本文采用大涡模拟方法细致刻画了返回舱类钝体外形在高雷诺数再入过程中的分离和转捩等物理现象,获得了返回舱底部流动形态以及稳定性特征. 从肩部剪切失稳、底部流动结构失稳、尾迹发展区以及远尾迹区的耦合失稳等多个角度分析了返回舱外形的底部流动失稳机制.研究发现, 返回舱类外形底部流动稳定性主要存在两类失稳模式即肩部剪切失稳模式以及底部流动结构失稳模式,二种模式存在耦合效应, 同时在远尾迹湍流区域存在类卡门涡街的振荡行为.这些认识为理解返回舱外部扰动因素对底部流动的作用机理及返回舱稳定性控制提供了基础理论支撑.

     

    Abstract: There are some problems of return capsule during reentry process, such as high heat flux of shoulder, prediction of base drag and unsteady vibration. Solve these problems, the key is accurate identification of separation and transition physical phenomenon. In this paper, separation and transition phenomenon of return capsule during reentry process under high Reynolds number condition are investigated by means of large eddy simulation (LES), base flow patterns and stability characteristics of return capsule are obtained. Physical mechanisms of base flow instability are analyzed from the aspects of shoulder shear instability, base flow structure instability and wake region instability. The results show that base flow stability of return capsule all includes shoulder shear instability mode and base flow structure instability mode, there is interaction between the two instability modes, there is are oscillation characteristics of Karman vortex street in the far wake turbulent region. These understandings support mechanism of the effect of external disturbances on the base region and stability control of return capsule in the theory.

     

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