Transonic Flutter Analysis Using Coupled CFD-CSD Analysis and New Reduced Order Modeling Technique

Abstract

A new reduced-order modeling (ROM) technique based on the coupled CFD-CSD aeroelastic response with a reduced set of state variables is presented in this paper. Assuming that the structural model is known a priori either from an analysis or a test and using linear transformations between structural and aeroelastic states, it is possible to innovatively identify aerodynamic information from sampled time histories of the aeroelastic system. More specifically given a finite set of structural modes the method extracts generalized aerodynamic force matrix corresponding to these mode shapes. Once the aerodynamic forces are known, an aeroelastic reduced-order model can be constructed in discrete-time, state-space format by coupling the structural model and the aerodynamic system. The presented reduced-order model is suitable for constant Mach, varying density (CMVD) flutter analysis. Three-dimensional AGARD 445.6 wing model is considered for numerical verification and the present flutter analysis results show good agreement with the experimental data.