Low speed and high angle of attack are problems that must be faced in vertical launching missiles. A natural asymmetric vortex phenomenon occurs at a low speed and high angle of attack of a slender body. In this paper, the Detached Eddy Simulation (DES) method is adopted to simulate the asymmetric flow of a slender body at a high angle of attack. The influence of roughness is analysed from the flow field and pressure distribution. And the DES method is verified by comparing it with the wind tunnel test results. The flow fields of the four models with the surface roughness of 0, 0.8, 5, and 100 are compared. The downstream flow still appears asymmetric when the surface is smooth, indicating that the stability of the flow field is not enough to maintain the symmetry of the flow field. The simulation results show that the adverse pressure gradient increases in the region where the boundary layer separates with the roughness greatly increasing, but the structure of the flow field at the head is slightly different. On the whole, the surface pressure and lateral force per unit length () transform alternately along the axial direction, and the period of alternating reverses increases with the increase of roughness. Finally, the pressure tends to be in equilibrium, and approaches zero. It should be noted that the distribution of is slightly different on the head, indicating that the asymmetry of pressure on the cylinder section is an important factor controlling the magnitude and the direction of lateral force. The influence of roughness on the flow around a slender body is acquired in this paper, and it has reference significance to the roughness problem of the actual missile.

中文翻译：

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粗糙度对细长体不对称流场的影响

低速、大迎角是垂直发射导弹必须面对的问题。细长体在低速大迎角时会出现自然的不对称涡旋现象。在本文中，采用分离涡模拟（DES）方法来模拟细长体在大迎角下的不对称流动。从流场和压力分布分析粗糙度的影响。并将DES方法与风洞试验结果进行对比验证。比较了表面粗糙度为0、0.8、5、100的四种模型的流场。当表面光滑时，下游流动仍然呈现不对称，说明流场的稳定性不足以维持流场的对称性。模拟结果表明，边界层分离区域的逆压梯度随着粗糙度的增大而增大，但头部流场结构略有不同。整体上，单位长度的表面压力和侧向力 ()沿轴向交替变换，交替反转的周期随着粗糙度的增加而增加。最后，压力趋于平衡，接近于零。需要注意的是，头部的分布略有不同，说明圆柱段压力的不对称性是控制侧向力大小和方向的重要因素。本文获得了粗糙度对细长体周围流动的影响，对实际导弹的粗糙度问题具有参考意义。