Estimation of Aeroelastic Characteristics of Aerospace Planes in Increasing Speeds

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The objective of this study is to propose a nonstationary prediction method which estimates stability (flutter or divergence) boundaries and the aeroelastic characteristics of airplane models tested in an increasing, i.e., nonstationary flow.The response of the wings subjected to flow turbulence is modelled by an ARMA process. The aeroelastic characteristics and stability margin are evaluated from the AR coefficients of the process determined with the aid of Akaike's AIC approach. The stability boundary is estimated through extrapolation of the stability margin evaluated in a subcritical flow range. The effectiveness of the present estimation method has been confirmed through application to experimental data obtained in low-speed and supersonic wind-tunnel tests.In addition, numerical simulation of aeroelastic response of a two-dimensional wing model in an incompressible turbulent flow was performed in order to clarify fundamental aspects of estimation based on this estimation method. An important confirmation of the simulation analysis is that the standard deviation of the stability margin evaluated from the AR coefficients decreases rapidly as the flow speed approaches the stability boundary, unlike the damping coefficient which is used in conventional methods. This fact provides a significance basis for the nonstationary prediction method in which the stability boundary is determined by drawing a straight line as the upper side of an envelope for scattering values of the stability margin.