A special prize from the European Space Agency (ESA) was given to Sébastien Deck, a CFD specialist at Onera, for his contribution to the understanding of flows around launcher afterbodies.
Sébastien Deck received his prize at the 7th European conference on aerothermodynamics for space transport held in Bruges from May 9th to May 12th.
Sébastien Deck has designed and developed a hybrid method for the simulation of flows particularly adapted to cases whereby the flow includes separated zones that are highly three-dimensional and unsteady. This method, called Zonal Detached Eddy Simulation (ZDES), allows for the cohabitation within the same simulation of an RANS-type Navier-Stokes model (relatively stationary general flow) and an LES-type model, localized in the separated zones (unsteady). This means that the most efficient (and most costly) model is only used when it is really necessary, resulting in acceptable simulation times.
The simulations of Sébastien Deck around the Ariane 5 base has helped to improve understanding of the flows around the launcher afterbody, which has made it possible for the agencies (Esa, Cnes) to better adapt certain instabilities of the launcher (this is why he received the prize). Afterbody unsteadiness leads to side-loads perpendicular to the ascent of the launcher.
The ZDES method, included in Onera’s aerodynamic simulation software “elsA’ and soon to be included in the “Cèdre” energetic software, is also useful to other applications such as civilian aircraft (buffeting prediction), helicopters, issues of stealth for jets and drones, and it could also be useful in other fields such as automobiles and hydrodynamics.
ZDES calculation of the launcher afterbody where we can appreciate the complexity of the flow.
Simulation of the phenomenon of buffeting observed at transonic speeds (uses the ZDES method in the separated zones).