飞翼无人机嗡鸣气动弹性响应分析

Buzz Aeroelastic Responses Analysis for a Flying Wing UAV

提出一种嗡鸣响应分析的CFD/CSD耦合方法,并采用气动结构松耦合技术研究了无尾飞翼无人机的方向舵嗡鸣响应及其引起的副翼、升降舵及襟翼的振动时域响应特性。首先建立较为详细的无尾飞翼无人机结构模型和气动模型,基于雷诺平均的N-S方程建立流体控制方程和结构动力学方程的耦合求解技术;气动与结构耦合交界面精确匹配,并选取三维插值技术进行耦合界面结构变形位移与气动力载荷数据的传递;基于LU-SGS子迭代的时间推进技术和HLLEW的空间离散方法进行气动载荷的计算,湍流模型采用SST湍流模型;其中气动动网格变形技术采用非结构动网格,动网格更新技术采用弹簧近似光滑和局部网格重构组合方法。首先进行飞翼无人机气动弹性响应特性分析,验证松耦合技术的合理性并为方向舵偏转引起的嗡鸣响应分析提供参考;其次在方向舵嗡鸣响应分析时在方向舵转轴端部设置方向舵偏转运动的约束,基于提出的气动结构松耦合方法计算无尾飞翼无人机方向舵偏转引起的方向舵嗡鸣和全机的方向舵、副翼、升降舵及襟翼振动的时域响应;并研究了旋转角频率和飞行高度参数变化对飞翼无人机全机振动响应的影响。研究结果表明旋转角频率对方向舵的偏转响应和副翼、升降舵及襟翼的振动响应频率影响较大;而飞行高度对嗡鸣气弹响应频率并没有影响;且方向舵是振动位移和结构变形的危险区域,研究方法及内容可为飞翼无人机工程振动分析提供参考。

Transonic rudder buzz responses and aileron, elevator, flap vibration time responses, which were based on the CFD/ CSD buzz coupled method, were presented for a tailless flying wing UAV. The RANS N-S equations and finite element methods, based on the detailed aerodynamic and structural model, were established. The interfaces between the structural and aerodynamic model were built with an exact match surface where load transferring was performed based on 3D interpolation. The LU-SGS iteration and HLLEW space discrete methods based on the SST turbulence model were used to calculate the aerodynamic force, in which the aerodynamic dynamic meshes used the unstructured dynamic meshes based on the combination of the spring-based smoothing and local remeshing methods. The firstly calculated aeroelastic responses of the flying wing UAV could provide a reference for the buzz responses analysis. The constraints of the rudder motions were fixed at the end of the flying wing UAV structural model, and based on the presented buzz aerodynamic structural coupling method, the flying wing UAV buzz responses and aileron, elevator, flap vibration time responses induced by the rudder motion were studied; the effects of rotating angular frequencies and heights on the vibration time responses were also given. The research results showed that： （1）the rotating angular frequency had a big effect on the rudder buzz and aileron, elevator and flap vibration responses frequency, but the height did not affect the response frequency; （2）the flying wing UAV rudder had the dangerous structural deformations. The research method and conclusions could provide a reference for the flying wing UAV engineering vibration analysis.