Effect of elastic deformation on flight dynamics of projectiles with large slenderness ratio
Effect of elastic deformation on flight dynamics of projectiles with large slenderness ratio
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DOI：
10.1016/j.ast.2017.09.029
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发表时间：
2017-12
影响因子：
5.6
通讯作者：
Ruhao Hua;Zhengyin Ye;Jie Wu
中科院分区：
文献类型：
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作者：
Ruhao Hua;Zhengyin Ye;Jie Wu
随着飞行速度和机动性的提高，现代大长径比弹丸的弹性变形已不容忽视。本文采用CFD技术求解非定常雷诺平均Navier-Stokes（URANS）方程。基于非结构网格框架，分别采用刚体运动网格和反距离加权变形网格技术处理飞行动力学引起的刚体运动和气动弹性引起的柔性结构变形。通过气动力耦合求解了六自由度动力学方程和静气动弹性方程。自由飞行和气动弹性两种情况下的数值计算结果与实验结果吻合较好，验证了数值方法的正确性。建立了X-X构型弹丸模型，研究了弹性变形对弹丸飞行动力学的影响。结果表明，弹性变形对纵向振动的影响大于质心运动，取向角的振动周期增大。此外，还对刚体模型在不同质心位置下的运动轨迹进行了仿真，结果表明，弹性变形会使气动中心前移，从而削弱静稳定裕度的裕度。最后，通过对压力分布的详细分析和比较，揭示了弹性变形导致气动中心移动，改变柔性弹飞行动力学特性的机理。
The elastic deformation of modern projectiles with large slenderness ratio cannot be ignored with the increasing of flight speed and maneuverability. Unsteady Reynolds-averaged Navier–Stokes (URANS) Equations are solved through CFD technique in this paper. Based on the frame of unstructured mesh, techniques of rigid-motion mesh and inverse-distance-weighted (IDW) morphing mesh are adopted to treat the rigid motion caused by flight dynamics and flexible structure deformation due to aeroelasticity, respectively. Moreover, the six degree of freedom (SDOF) dynamic equations and static aeroelastic equation are solved through the aerodynamic coupling. Numerical results of both free flight case and aeroelastic case calculated by the in-house code agree well with the experimental data, validating the numerical method. A projectile model with X–X configuration is constructed to investigate the effect of elastic deformation on the flight dynamics. Comparison results show that the longitudinal oscillation is more affected by the elastic deformation than the centroid motion, and the oscillation cycle of the orientation angle increases. Furthermore, the trajectories of rigid models with various centroid locations are simulated, illustrating that the elastic deformation could move the aerodynamic center forward and weaken the margin of the static stability margin. In the end, detailed analysis and comparison of the pressure distribution indicates the mechanism by which the elastic deformation leads to the movement of the aerodynamic center and changes the flight dynamic characteristics of the flexible projectile.