Assessment of Computational Fluid Dynamics acoustic prediction accuracy and deflector impact on launch aero-acoustic environment

Abstract

The vibroacoustic loading generated during the launch of space vehicles can cause the failure of electronic and mechanical components. Therefore, predicting and mitigating these vibroacoustic levels are crucial to improve the reliability of launchers and payload comfort. Because a properly designed flame deflector can significantly reduce the acoustic pressure level, the aeroacoustics characteristics of diverse types of flame deflectors must be understood. Three different deflector geometries have been analysed: two wedge-type deflectors and a flat deflector since the impact on a flat plate is the simplest case of reflection. The sound generation and propagation were studied using dedicated computational fluid dynamics. Additionally, experimental data has been used to evaluate the accuracy and performance of two numerical models. On the one hand, an Unsteady Reynolds-Averaged Navier-Stokes model running in central processing units, CPU. On the other hand, a Large Eddy Simulation model efficiently designed to run on graphics processing units, GPU. The second model showed excellent agreement at a low computational cost. To assess noise generation, the main shock waves were identified, and the evolution of the generated sound pressure was assessed. Moreover, the sound pressure levels at the fairing surface have been studied.