Immersed Boundary Simulations of Aeroacoustics Phenomena in Solid Rocket Motors

The combustion of heterogeneus solid propellants are characterized by velocity fluctuations which have a fundamental effect on the turbulence development and on the onset of aeroacoustic instabilities. In this work, following open literature, we propose a parametric study to develop a specific mass-injection boundary condition able to account for such fluctuations. T his n ew p ropellant b oundary c ondition is implemented in a advanced flow s olver w hich a dopt t he immersed b oundary m ethodology t o d eal with complex geometries and applied to a real rocket motor inspired by the second stage of the european VEGA launcher. The numerical results show that it is possible to tune the model in order to correctly reproduce the amplitude and the main frequency of the pressure oscillations which develop inside the combustion chamber.