Abstract
Large solid propellant rocket motors may be subjected to aero-acoustic instabilities arisingfrom a coupling between the burnt gas flow and the acoustic eigenmodes of thecombustion chamber. Given the size and cost of any single firing test or launch, it is offirst importance to predict and avoid these instabilities at the design level. The mainpurpose of this paper is to build a numerical tool in order to evaluate how the coupling ofthe fluid flow and the whole structure of the motor influences the amplitude of the aeroacousticoscillations living inside of the rocket. A particular attention was paid to thecoupling algorithm between the fluid and the solid solvers in order to ensure the bestenergy conservation through the interface. A computation of a subscaled version of theAriane 5 solid propellant engine is presented as illustration.