Study of flame response to transverse acoustic modes from the LES of a 42-injector rocket engine

Annafederica Urbano (1) , Quentin Douasbin (2) , Laurent Selle (2) , Gabriel Staffelbach (3) , Bénédicte Cuenot (3) , Thomas Schmitt (4) , Sébastien Ducruix (4) , Sébastien Candel (4)

1 SAFRAN Group
2 IMFT - Institut de mécanique des fluides de Toulouse
3 CERFACS - Centre Européen de Recherche et de Formation Avancée en Calcul Scientifique
4 EM2C - Laboratoire d'Énergétique Moléculaire et Macroscopique, Combustion

The Large-Eddy Simulation of a reduced-scale rocket engine operated by DLR has been conducted. This configuration features 42 coaxial injectors fed with liquid oxygen and gaseous hydrogen. For a given set of injection conditions the combustor exhibits strong transverse thermo-acoustic oscillations that are retrieved by the numerical simulation. The spatial structure of the two main modes observed in the LES is investigated through 3D Fourier analysis during the limit cycle. They are respectively associated with the first transverse and first radial resonant acoustic modes of the combustion chamber. The contributions of each individual flame to the unsteady heat release rate and the Rayleigh index are reconstructed for each mode. These contributions are in both cases low in the vicinity of velocity anti-nodes and high near pressure anti-nodes. Moreover it is noticed that these pressure fluctuations lead to large velocity oscillations in the hydrogen stream. From these observations, a driving mechanism for the flame response is proposed and values for the gain and phase of the associated flame transfer function are evaluated from the LES.

Mots clés: Large-Eddy Simulation; Rocket propulsion; Transverse combustion instability; Flame transfer function; Rayleigh index

Domaines: Mécanique des fluides [physics.class-ph]

Annafederica Urbano, Quentin Douasbin, Laurent Selle, Gabriel Staffelbach, Bénédicte Cuenot, et al.. Study of flame response to transverse acoustic modes from the LES of a 42-injector rocket engine. Proceedings of the Combustion Institute, 2017, vol. 36 (n° 2), pp. 2633-2639. ⟨10.1016/j.proci.2016.06.042⟩. ⟨hal-01551126⟩