为了深入理解以周期变距为激励的失速颤振特性,通过弹性机构输入周期变化角度,进而控制NACA 0012翼型攻角变化的实验装置,探究弹性约束下翼型攻角的变化规律以及有/无弹性约束时气动力对翼型做功的差异.实验结果表明:攻角的变化规律在不同驱动频率和扭转刚度下表现出4种特殊形态;翼型攻角的变化主频与驱动频率一致,并出现攻角的两周期振动,此时自然频率与驱动频率之比接近π/2.进一步分析气动力对翼型的能量传递,发现周期变距激励的失速颤振与无激励输入颤振有显著差异,分析表明气动力即使在一个周期内做负功,仍可能改变弹性结构的能量传递而使振动幅度增加.%The resultant behavior of airfoil incidence and the differences of work done by aerodynamic forces under/without torsional system are investigated,in order to better understand the characteristics of stall flutter with cyclic pitch input.The incidence of NACA 0012 airfoil was controlled by cyclic pitch input through a torsional elastic system.As results,there are four kinds of special forms of attack angle variation regularities under different driving frequencies and torsional rigidity.The main frequency complies with the driving frequency,while a period-2 oscillation is also observed,where the ratio of driving and natural frequency is approximately π/2.Further analysis considering the energy transfer of aerodynamic force on the airfoil shows that the mechanism of energy transfer of stall flutter with cyclic pitch differs from that inspired by perturbation,which means the elastic structure will be changed and the flutter amplitude can still be increased,even if negative work is done by aerodynamic forces.
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