风洞自由飞模型俯仰阻尼导数的提取方法

本文介绍了提取风洞自由飞模型俯仰阻尼导数的一种方法。使用非线性微分方程对模型姿态角进行参数辩识而得到以瞬时角位移表示的俯仰阻尼导数。假定在每个振动周期内模型阻尼变化小,且阻尼导数对称。使用 Kryloff-Bogoliuboff 方法对瞬时阻尼进行平均化处理便给出以角振幅表示的模型俯仰阻尼导数。这种角振幅表示法使模型非线性阻尼导数具有良好的重复性。因此,风洞自由飞模型非线性俯仰阻尼导数表示为角振幅的函数更为合理。而且在实验数据的角振幅变化范围内提供较为可靠的结果。

AN ACQUISITION METHOD OF PITCH DAMPING DERIVETIVES OF A BODY IN WIND TUNNEL FREE-FLIGHT TESTING

A method to the problem of obtaining nonlinear pitchdamping derivatives from an observed angular motion of a body in tun-nel free-flight testing is presented.The pitch damping derivatives asa function of instantaneous angular displacement are obtained to fit theobserved angular data by the nonlinear differential equations of motion.It is assumed that the damping per cycle is small,the damping coef-ficient is symmetrical.Then the pitch damping derivatives as a functionof oscillation amplitude are obtained by applying the Kryloff-Bogoliuboffequivalent linearization technique to instantaneous damping.These damp-ing derivatives as a function of oscillation amplitude have a good preci-sion.In conclusion,the nonlinear pitch damping derivatives represent-ed as a function of oscillation amplitude are more suitable for windtunnel free-flight testing,and the nonlinear pitch damping derivativesare reliable in the amplitude range of testing data.