Nonlinear Panel Flutter Analysis Based on an Improved CFD/CSD Coupled Procedure

摘要

Nonlinear aeroelasticity, caused by the interaction between nonlinear fluid and geometrically nonlinear structure, is studied by an improved CFD and CSD coupled program. An AUSMpw+ flux splitting scheme, combined with an implicit time marching technology and geometric conservation law, is utilized to solve unsteady aerodynamic pressure; The finite element co-rotational theory is applied to model geometrically nonlinear two-dimensional and three-dimensional panels, and a predictor-corrector program with an approximately energy conservation is developed to obtain nonlinear structure response. The two solvers are connected by Farhat's second order loosely coupled method and the aerodynamic loads and structural displacements are transferred by boundary element method. With the application on the solution of panel flutter problems for supersonic, transonic and subsonic Mach numbers, representative limited cycle oscillations appear when geometric nonlinearity and aerodynamic nonlinearity are considered. The flutter boundary and amplitude of limit cycle oscillation are discussed and compared with the work of Dowell and Gordnier. The program is also used to compute the nonlinear elastic response of AGARD 445.6 wing, and the results show that improved procedure presents a better stability than conventional method.