Study of Fast Prediction Method for Transonic Flutter Boundary Using Radial Basis Function

Abstract

A spectral volume method for hybrid unstructured mesh developed earlier is built in an aeroelastic code to determine transonic flutter boundary of AGARD 445.6 wing. It is shown that the computed transonic dip of flutter boundary reasonably agrees with the experimental data. In the present study, we focus on to develop a fast numerical method for evaluating the bottom of transonic dip. In order to reduce the number of computational cases to determine the flutter boundary, an interpolation method using the radial basis function is examined. The initial sampling points are sparsely distributed over the entire parameter plane to roughly determine the flutter boundary by interpolating damping ratio of wing oscillation. Then, based on the consideration of load distribution over the wing, some additional sampling points are introduced in the region where the transonic dip likely appears. It is demonstrated that the present approach allows us to evaluate the bottom of transonic dip with less computational efforts for the present problem. Discussions are included to examine the possible efforts of the arrangement of initial sampling points and interpolation method on the shape of flutter boundary near the dip.