Computed Gust Response of An Aircraft. The Relative Effect of Various Degrees of Freedom

摘要

A typical jet transport aircraft has been modelled with increasing numbers of degrees of freedom. Transfer functions and spectral parameters, A and N sub o, were evaluated using tow gust models. The first gust model consisted of gust variations in the streamwise direction alone. The second model, a two dimensional gust model, is made up of variations in both the streamwise and spanwise direction. In both of these cases a von Karman gust spectrum, with integral scale of turbulence of 688m, was assumed. As the degree of flexibility of the model was augmented from one to five degrees of freedom the spectral parameter, A, increased by 8%. The value of N sub o was strongly biased by the high frequency response of the model. Therefore it was concluded that trends in N sub o with system flexibility, could not be determined accurately until the asymptotic behaviour of the response is known. For the five degree of freedom model the introduction of spanwise variations in gust caused only slight variations in the spectral parameters A and N sub o. Keywords: Power spectra; gusts; Turbulence; Dynamic response. (Australia)