飞行高度摄动的鲁棒颤振计算方法

Calculation Method for Robust Flutter Based on Altitude Perturbation

提出了一种以飞行高度作为摄动变量,利用结构奇异值理论来进行鲁棒颤振计算的方法。将标准大气模型中的高度与大气密度,高度与声速的关系拟合成为多项式表示的函数关系,从而将动压和飞行速度表示成飞行高度的函数,使得系统以飞行高度为惟一的摄动变量。然后利用线性分式变换考虑了广义刚度和广义阻尼的不确定性,建立整个系统完整的状态空间模型,使用结构奇异值理论计算颤振裕度。该方法适用于固定马赫数的飞行颤振试验和飞行包线扩展。

A method for robust flutter computation is presented by using flight altitude as a perturbation variable. The air density and the sound speed of the standard atmosphere model are approximated as a polynomial function of the altitude, and then the dynamic pressure and the flight speed can be expressed as a function of the flight altitude. So the flight altitude becomes the only variable in the aeroelastic system. The uncertainty of generalized stiffness and damping can be formulated by linear fractional transformation （LFT） tools and the state-space models are generated in μ- analysis framework. Finally, the robust flutter margins can be computed by SSV theory. The method can be used in Mach number constant flight flutter test and flight envelope expansion.