Accurate numerical simulation on the structural response of the VEGA payload fairing using modal coupling approach

Structural aeroacoustic interactions are of great interest in the design and manufacture of aerospace structures. During the lift off and the early phases of the launch various external loads like steady accelerations, random and broadband frequency vibrations, acoustic loads due to jet noise and fluid–structure interactions act on the lightweight panel structure of the payload fairing. Thereby internal vibrational loads and instability effects may be caused by the interaction of various mechanical loads and acoustic noise acting on the cylindrical shell structure. Within the project “Prediction of Acoustic Loads on Space Structures” funded by the European Space Agency (ESA) an aeroelastic coupling approach has been built up. Therein, the aerodynamic loads on the VEGA payload fairing (PLF) have been determined for different flight conditions by the use of the open-source CFD solver SU2. Due to the different discretization between the computational fluid dynamics (CFD) and computational structural dynamics (CSD) mesh the approach of Radial Basis Function (RBF) has been used to interpolate the resulting pressure distribution onto the structural model. According to that the dynamic response of the PLF has been analyzed by taking the basic aerodynamic forces, structural vibration and acoustic pressure fluctuations into account. An intrinsic part of this work is the numerical simulation and assessment of the interaction between structural vibrations, transonic flow and acoustic pressure fluctuations during the early launch phase.