Effect of the fluid–structure interaction on solid rocket motors instabilities

Abstract

Large solid propellant rocket motors may be subjected to aero-acoustic instabilities arising from a coupling between the burnt gas flow and the acoustic eigenmodes of the combustion chamber. Given the size and cost of any single firing test or launch, it is of first importance to predict and avoid these instabilities at the design level. The main purpose of this paper is to build a numerical tool in order to evaluate how the coupling of the fluid flow and the whole structure of the motor influences the amplitude of the aeroacoustic oscillations living inside of the rocket. A particular attention was paid to the coupling algorithm between the fluid and the solid solvers in order to ensure the best energy conservation through the interface. A computation of a subscaled version of the Ariane 5 solid propellant engine is presented as illustration.