Active Flutter Suppression of a Wing Section in a Compressible Flow

In this paper, a unified method for the computation of the unsteady aerodynamic forces in the Laplace domain for a wing section in subsonic, sonic and supersonic potential flows is presented. The subsonic solution is a new development based on the pressure mode method. The unsteady aerodynamic forces are evaluated in the Laplace domain by an efficient method for computing the kernel. The sonic potential flow solution is an extension of the solution for the frequency domain to the Laplace domain. Analytical expressions for the unsteady pressure coefficient and the unsteady aerodynamic forces in the Laplace domain are obtained for this flow regime. The method is validated in these regimes with existing theories in the frequency domain, and its application to flutter computation is provided for different Mach numbers by the use of the p-method. Active flutter suppression for a wing section with three degrees of freedom has been studied, and an adequate control law has been obtained. Using the proposed approach allows to calculate the unsteady aerodynamic forces directly in the Laplace domain, avoiding the inconvenience of the curve fitting from the frequency to the Laplace domain. In particular, this work can be used as a base for the application of other procedures for flutter suppression in the transonic regime.