机翼摇晃运动研究

A STUDY OF WING ROCK

机翼摇晃运动作为现代高机动性飞机在失速迎角附近飞行时出现的一种现象而受到普遍重视.迄今为止,对机翼摇晃的研究工作一般沿两种途径进行。一种为分析产生机翼摇晃的气流流动机理;另一种根据机翼摇晃时飞机运动的特点进行讨论。本文从飞机六自由度方程入手,建立描述大迎角机动飞行的空气动力模型。在此基础上,按照微分方程定性理论和传播矩阵,研究机翼摇晃的产生原因和飞机运动的特点。结果认为,机翼摇晃是一种非线性系统的Hopf分支现象.对具有中等后掠角机翼的飞机,产生机翼摇晃的主要原因是滚转阻尼力矩随迎角和侧滑角的变化.

As a phenomenon which occurs in modern high performance aircraft when they fly around the stall angle of attack, wing rock has been paid widespread attention. So far, the study on wing rock has been carried out along two approaches.One is to analyse the fluid mechanism of wing rock, the other is to study the characteristics of wing rock motion.According to the later approach, this paper begins with the general equations of aircraft unsteady motion. Then, the aerodynamic model which discribing aircraft manoeuver at high angle of attack is setted up. Furthermore, by using the qualitative theory of ordinary differential equations and the propagational matrix, the reason of causing wing rock and the characteristics of aircraft motion are discussed. The results show that, wing rock is a Hopf bifurcation phenomenon of nonlinear dynamic system. For the aircraft with moderate swept wing, the main reasons of causing wing rock are the variations of roll damping moment with the angle of attack and the sideslip angle.