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摘要:
航空飞行器通过翼尖铰接机构复合飞行时的气动耦合效应，会造成飞机产生不同于其单独飞行时的动力学特性，出现复合飞行安全问题。为研究翼尖铰接复合飞行器的动力学特性，使用Newton-Euler方法和Robberson-Wittenburg方法建立了双机组成的翼尖铰接复合飞行器多刚体系统整体和内部的7自由度非线性动力学和运动学方程组。在气动准定常假设下建立双机复合系统非耦合气动力表达式，基于CFD方法开展复合飞行器系统的三维实体建模和非结构网格划分工作，获取复合飞行器系统的气动力数据。搭建动力学仿真平台，开展准配平方案和全配平方案下的动力学仿真。仿真结果表明：准配平方案下飞行器无法持续稳定飞行，而全配平方案下复合飞行器系统各运动参数在仿真时间内始终趋于稳定。在全配平方案下，使用小扰动假设的非解耦线性化方法重新整理7自由度动力学方程组，研究复合飞行器系统运动模态的特征值中出现的2个发散新模态，根据对应的特征向量发现2个发散模态分别由相对滚转角度和角速度主导，同时也比较分析了其他运动模态相比单机飞行时的特性变化规律。
Abstract:The aerodynamic coupling effect of the composite flight of aircraft via wingtip-jointed structure determines the dynamic characteristics different from those of its independent flight, where safety risks might exist. In order to investigate the dynamic characteristics of the wingtip-jointed composite aircraft, the Newton-Euler method and Robberson-Wittenburg method are used to derive the 7-degree-of-freedom nonlinear dynamics and kinematics equations of the multi-body system of the wingtip-jointed composite aircraft composed of two aircraft. Under the aerodynamic quasi-steady assumption, uncoupling aerodynamic force formula for two-aircraft composite system is established, and the composite aircraft system's three-dimensional modeling and unstructured meshing are further carried out based on the CFD method to obtain the aerodynamic data. The dynamic simulation platform is built, and the dynamic simulations under the quasi-trimming strategy and the full-trimming strategy are carried out on the dynamic simulation platform. The result proves that the aircraft cannot continue to fly stably under the quasi-trimming strategy, while the motion parameters of the composite system under the full-trimming strategy always tend to be stable. Under the full-trimming strategy, the decoupling linearization method using small disturbance hypothesis is used to rearrange the terms of the 7-degree-of-freedom dynamic equations, and study the two new divergent eigenvectors in the eigenvalues of the composite system motion modes, which shows that the two divergent modes are dominated by the relative roll angle and angular velocity. Meanwhile, the characteristics of other modes compared with the single-plane flight are summarized and analyzed.
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Key words:
- new-concept aircraft /
- modeling and simulation /
- CFD method /
- dynamic characteristics /
- modal analysis
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图 4 翼尖铰接复合飞行器机体坐标系
Figure 4. Airframe coordinate system of wingtip-jointed composite aircraft
图 5 翼尖铰接复合飞行器内部运动分析
Figure 5. Internal motion analysis of wingtip-jointed composite aircraft
图 6 复合飞行器系统ANSYS非结构网格划分
Figure 6. Unstructured grid generation of composite aircraft system by ANSYS
图 7 翼尖铰接复合飞行器系统动力学仿真模块
Figure 7. Dynamic simulation module of wingtip-jointed composite aircraft system
图 8 翼尖铰接复合飞行器动力学响应仿真结果
Figure 8. Dynamic response simulation results of wingtip-jointed composite aircraft
表 1 气动力数据库获取方法
Table 1. Aerodynamic database acquisition method
CFD仿真工作内容 气动参数 建模方法 复合运动特征参数气动导数计算 CDφ12, CLφ12，CMφ12等 稳态流动迭代仿真
湍流格式采用Spalart-Allmaras模型
求解算法Simple
采用二阶迎风格式
对控制方程进行离散推进复合系统舵面偏转操纵导数计算 CDδ, CLδ，CMδ等 基本气动参数计算 静导数CDα, CLα, CMα等 动导数 
Zaero软件非定常气动计算 
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表 2 复合飞行配平方案
Table 2. Composite flight trimming strategy
舵面参数 准配平方案 全配平方案 右侧飞机 左侧飞机 右侧飞机 左侧飞机 油门杆位移/% 58.70 58.70 54.40 54.40 升降舵偏角/(°) 3.98 3.98 4.57 4.57 副翼偏角/(°) 0 0 -3.80 3.80 方向舵/(°) 0 0 0 0
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表 3 运动模态分析
Table 3. Motion modal analysis
运动模态 特征值 模态名称 单机运动模态 -0.007 7+0.049 7i 长周期模态 -0.007 7-0.049 7i 长周期模态 -2.300 纵向模态1 -0.055 2 纵向模态2 -4.169 滚转模态 -0.022 2 螺旋模态 -0.012 2+0.011 8i 荷兰滚模态 -0.012 2-0.011 8i 荷兰滚模态 双机复合运动模态 -0.004 3+0.053 4i 长周期模态 -0.004 3+0.053 4i 长周期模态 -2.270 纵向模态1 -0.048 6 纵向模态2 -6.658 滚转模态 -0.008 螺旋模态 -0.091 9+0.134 6i 荷兰滚模态 -0.091 9-0.134 6i 荷兰滚模态 0.143 9 复合运动模态1 1.703 复合运动模态2
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表 4 模态参数分析
Table 4. Modal parameter analysis
模态名称 单机/复合 ωn/(rad·s-1) ε ω/(rad·s-1) T/s t1/2/s N1/2/次 t2/s 模态特点 长周期模态 单机 0.050 0.154 0.049 7 126.42 90 0.72 收敛 复合 0.054 0.080 0.053 4 117.66 161.16 1.37 收敛 纵向模态1 单机 2.3 1 0 0.301 收敛 复合 2.27 1 0 0.305 收敛 纵向模态2 单机 0.055 2 1 0 12.53 收敛 复合 0.048 6 1 0 14.26 收敛 滚转模态 单机 4.169 1 0 0.166 2 收敛 复合 6.658 1 0 0.104 1 收敛 螺旋模态 单机 0.022 1 0 31.5 收敛 复合 0.008 1 0 86.625 收敛 荷兰滚模态 单机 0.016 9 0.722 0.011 8 532.5 56.8 0.106 7 收敛 复合 0.163 0.564 0.134 6 46.7 7.541 0.161 5 收敛 复合运动模态1 复合 0.143 9 1 0 4.813 发散 复合运动模态2 复合 1.703 1 0 0.407 发散
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