Static aeroelastic simulation using CFD, comparison with linear method

This investigation has partly been carried out under a contract awarded by The Netherlands Ministry of Defence monitored by the Royal Netherlands Air Force and as part of NLR's Basic Research Programme. The Netherlands Ministry of Defence and the Royal Netherlands Air Force have granted NLR permission to publish this report. Summary This paper presents static aeroelastic simulations of fighter-type aircraft in transonic flow at various load factors. The linear approach of NASTRAN and NLR in-house developed ENFLOW computational aeroelastic simulation (CAS) system are employed in the simulation. ENFLOW CAS system, based on a CFD method employing the Euler/Navier-Stokes equations, solves the aeroelastic governing equations in a loosely-coupled manner. Prior to discussing the applications, several important aspects of the method will be described. Applications of the method are presented for fighter aircraft in a simple air-to-air configuration subjected to transonic flow. Two types of trimming have been used, the [C L ] − [α] trim strategy and [C L , C MP ] − [α, δ H ] trim strategy. The efficiency and robustness of the method are shown by the quick convergence during the iteration to solve the sets of equations, i.e. aerodynamic, structural, and trim equations. As expected, for transonic flows, differences are observed between the results of ENFLOW and NASTRAN. Several possible causes of the differences are discussed. The deflection relative to the deflection at level flight compares well with the results of flight test.

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