飞机的伺服-气动弹性稳定性

现代飞机的自动控制系统都具有控制与增稳两种功能,它通过伺服系统与控制面相连。这种系统与控制对象——飞机之间形成一个闭合回路,如图1所示。考虑到控制系统与飞机两者间动力学特性的相互作用,构成一系列性质各异的回路问题。根据他们不同的外部条件和涉及面的特性差异,形成了多种现象,其中一个引人注目的问题就是闭合回路的稳定性问题。通常在把控制系统或结构作为单独分支而设计时是稳定的,而把它们串联起来成为一个整体时,系统的稳定性就发生了变化。

AIRCRAFT SERVO-AEROELASTICITY STABILITY

A dynamic stability analysis approach to an airplane equipped with automatic-control systems is demonstrated in this paper. As this sort of stability problem is due to the interaction between auto-control systems and structural vibration modes, it can be regarded as a kind of servo-aeroela-sticity instability phenomenon and it can also be refered to as servoflut-ter in the case of flight.This paper introduces two technical approachs to solving the previous problems. The numerical calculation of a complete system including unsteady aerodynamic forces is presented. In order to observe the influnce of the control systems on the airplane flutter, results of both open and closed loop calculations are illustrated with Nyquist and V-G diagrams.The results of calculation indicate that servo-aeroelasticity problem should be highly regarded in the process of airplane design and it is necessary to select a suitable notch filter for the control systems.