CERFACS CERFACS Scientific Activity Report Jan. 2010 – Dec. 2011

COMPUTATIONAL FLUID DYNAMICS
FIG. 2.4: Typical probability map for the success rate of ignition after energy deposit by a sparking device
obtained in the Mercato configuration of ONERA, through the statistical analysis of non-reacting LES
predictions.
[15](see Fig. 2.3),[CFD30]
on the Mascotte experiment of ONERA. A first version was available in 2008, which has been since
consolidated (in terms of numerics and physics) by A. Ruiz (PhD, CIFRE Snecma), who performed DNS
of transcritical mixing layers (Fig. 2.5). The next step is to couple such simulations with heat transfer, to
study the impact on flame stabilization and heating of the solid parts (PhD of R. Mari, CNES fellowship).
The solver is now sufficiently mature for industrial applications : it is used to study the highly unsteady flow
issuing from the coaxial injectors of the VINCI engine. The solver is installed at Snecma, under the C3S
application, for direct use by engineers. Training sessions have been organized to ensure a fast and correct
use of the code.
A second important aspect of liquid propulsion for rockets is ignition. It must be reliable, to guarantee 100%
success, but not ”violent” to avoid destructive pressure waves. However H2-O2 chemistry is very fast and
powerful, therefore delicate to control for smooth ignition. LES is helpful to study mixing and combustion
of both reactants in the exact real injector geometry. In this context, the initial work of Lacaze [14], studying
the ignition of one injector, has been continued in the PhD of JP. Rocchi to address the ignition of a set of
injectors and the driving mechanism of flame propagation from one injector to the other.
FIG. 2.5: Direct Numerical Simulation of a transcritical mixing layer.
[CFD60]
CERFACS ACTIVITY REPORT 135