DEVELOPMENT OF A NEW TOOL FOR STATIC AEROELASTIC ANALYSIS APPLIED ON THE SAAB GRIPEN FIGHTER AIRCRAFT

摘要

A new tool for static aeroelastic analysis has been developed. The objective has been to combine the best analysis tools and models from the two disciplines CFD (Computational Fluid Dynamics) and FEM (Finite Element Method) into a robust, easy to use, production tool. The aeroelastic tool is a Matlab program that controls the CFD solver Edge and the structural FEM program MSC-Nastran and uses the results for finding an aeroelastic solution. Methods for transferring pressure loads from the CFD surface mesh to corresponding FEM mesh and vice versa, transferring structure deformations in the opposite direction were developed and implemented into the code. Also a new method for deforming the CFD volume mesh was invented and implemented. The static aeroelastic analysis, which is an iterative process, continues until a preset convergence criterion is reached. Typical aeroelastic analysis requires 3-4 times as long execution time as an ordinary (rigid geometry) CFD analysis. Within the European ALEF project, static aeroelastic analyses of wind tunnel tests were performed in order to test and verify the new methods and program. A passenger type wing with a deflected aileron was analyzed at high dynamic pressures with considerable structure deflections. Simulated aeroelastic results came very close to test data. Just recently aeroelastic analysis of the Saab JAS39 Gripen fighter has been initiated and preliminary results are promising. Both the Nastran and the Edge models are large and complex with many rather flexible control surfaces.