基于非线性气动力的失速颤振计算与试验研究

CALCULATION AND EXPERIMENTAL STUDY OF STALL FLUTTER BASED ON NONLINEAR AERODYNAMICS

飞行器大攻角飞行过程中的动态失速会导致结构自激扭转或俯仰运动,造成非线性失速颤振现象,直接影响飞行器飞行安全与结构安全。该文对标准Leishman-Beddoes(L-B)非线性非定常气动力模型进行马赫数修正,使其适用于低速不可压情形的动态失速气动力计算,然后基于二元翼段气动弹性模型,采用Newmark时域推进方法进行工程失速颤振计算。依据计算结果设计并完成了二元翼段失速颤振风洞试验。试验结果表明,多数试验状态,基于L-B模型的失速颤振计算结果与试验结果均吻合较好。结果验证了修正的L-B模型可以用来进行低速大展弦比平直翼段翼型的失速颤振工程分析与极限环振荡评估,同时,失速颤振速度与极限环幅值受初始攻角的影响很大。

The dynamic stall in the flight of the aircraft with a large angle of attack will lead to the self-excited torsion or pitch motion of the structure,causing nonlinear stall flutter,which will directly affect the flight safety and structural safety of the aircraft.In current study,the standard Leishman-Beddoes nonlinear unsteady aerodynamic model is modified by Mach number to make it suitable for the calculation of dynamic stall aerodynamic in the case of low speed incompressibility.Then,based on the two-element segment aeroelastic model,Newmark time-domain propulsion method is adopted for the calculation of engineering stall flutter.The stall flutter wind tunnel test is designed and completed based on the calculation results.The experimental results show that the stall flutter calculation results based on L-B model are in a good agreement with the experimental results in most experimental cases.The research results also verified that:the modified L-B model can be used for stall flutter engineering analysis and for the limit cycle oscillation evaluation of low-speed aircraft with high aspect ratio,and the stall flutter speed and limit cycle amplitude are considerably affected by the initial angle of attack at the same time.