High-fidelity simulations of the aeroacoustic environment of the VEGA launch vehicle at lift-off

The lift-off of space launch vehicles generates strong acoustic waves that interact in a complex and potentially dangerous way with the launch facility and the launcher itself. Engineering tools developed in the past to predict the strong acoustic radiation and the peak acoustic loads during the first seconds of the launch have a limited validity and are not able to provide reliable predictions. For this reason, in order to better identify the noise generation sources and to assess the effects of acoustic mitigation measures, it is fundamental to develop and validate more advanced computational models able to capture the transient flow induced by the ignition of the motors. In this work, we present high-fidelity 3D Large Eddy Simulations of the acoustic field produced by the lift-off of a realistic space launcher. A state-of-the-art, high-order, GPU accelerated, compressible solver is used to simulate the highly unsteady interaction of the exhaust plume from the launcher's nozzle with a realistic launch pad, whose geometry has been modelled by Immersed Boundary Method. The results obtained demonstrate the capability of our solver to provide accurate predictions compared to flight measurements of real configurations, despite the challenging scenario in terms of operating conditions and geometry. Moreover, wavelet analysis proves to be an appropriate tool to pinpoint and characterise the overpressure mechanisms that take place in the transient evolution of the flow.