大柔性飞机非线性飞行载荷分析及优化

 大柔性飞机在气动力作用下产生较大的弯曲变形,线性理论难以获得比较合理的载荷分析及优化解答。为了综合考虑结构气动非线性效应的影响,飞机结构由相互连接的几何非线性欧拉梁表示,升力面由顺来流方向沿展向分布的可压缩马蹄涡网络表示,通过多控制面协调偏转对飞行载荷进行优化。算例表明：随着变形增大线性分析结果将产生误差,最大误差接近20%;通过协调偏转升降舵与机翼上的4组控制面显著减缓了翼根弯曲载荷13.6%。得出以下结论：结构弯曲效应将导致升力损失,线性理论的分析结果将产生显著误差;多控制面协调偏转方法可有效减缓结构载荷。

Nonlinear Flight Load Analysis and Optimization for Large Flexible Aircraft

Large flexible aircraft tend to produce great bending deformation under aerodynamic force, so that it is difficult to obtain their load analysis and optimization solutions by means of the linear theory. In order to consider both the structure and aerodynamic nonlinearity, the structure is denoted by joined geometrical nonli-near Euler beams, while the aerodynamic model employs a spanwise compressible horseshoe vortex lattice, and the deflecting multiple control surfaces are coordinated to optimize the flight loads. Numerical results show that with the increase of aircraft deformation the linear analysis results will produce errors up to 20%. Through coordinating and deflecting the four groups of control surfaces located on the wing and the elevator, the wing root bending moment load is alleviated by 13.6%. It is concluded that structure bending effect leads to lift loss, which explains why linear theory analysis produces significant errors, and that coordinating and deflecting multiple control surfaces can alleviate structure loads effectively.