Improving the design of reusable rocket engines is a significant challenge in today's competitive environment for launching low-cost payloads. The jet flows from multiple engine bays in a reusable launcher interact in complex ways, creating intricate flow phenomena, especially within recirculation zones, turbulent mixing, and intense thermochemical gradients, particularly in boundary layers. Nevertheless, predicting wall heat flux within the framework of Large Eddy Simulation remains prohibitively expensive and presents considerable technical challenges. An accurate modeling of the boundary layer is therefore essential for predicting heat transfer in reactive flows that could compromise material integrity and flight stability. Those effects are challenging to model in the case of methane combustion, while this fuel will be massively used in various European engines, such as the Prometheus. 

Ultimately, more accurate predictions of nozzle thermal fluxes at the walls will allow for better estimation of an engine's lifespan for reuse. This doctoral project aims to develop a multiphysics numerical approach for simulating a reactive boundary layer in the supersonic regime by coupling compressible Navier-Stokes equations with chemical kinetic models. The goal is to accurately capture the complex interactions between gas dynamics, chemical reactions, and thermal effects near the walls. In this context, CNES is collaborating closely with Cerfacs [1] as part of the Aérothermodynamique des Tuyères et Arrière-Corps (ATAC) research group.

The primary objective of this doctoral project is to develop a high-fidelity wall boundary condition capable of modeling phenomena within a reactive boundary layer in a supersonic regime. This model will incorporate the interaction between air and burnt gases resulting from methane/oxygen combustion [2], robust discretization schemes to capture pronounced temperature gradients, and the coupling of chemistry, thermal effects, and compressible gas dynamics [3,4]. Special attention will be given to studying heat transfer mechanisms in the boundary layer, particularly in relation to rapid chemical reactions and aerodynamics. Initially, the model will be based on the assumption of thermochemical equilibrium, before integrating the effects of adverse pressure gradients.

Depending on the results, several chemical approaches might be investigated. Finally, the study will focus on a configuration representative of the Prometheus engine, such as the interaction between hot supersonic jets from the gas generators and the nozzle’s external wall. The wall model will be derived and validated using Direct Numerical Simulations, Wall-Resolved Large-Eddy Simulations, and, if available, with experimental data from supersonic wind tunnels or instrumented flight tests.

[1] G. Daviller, J. Dombard, G. Staffelbach, J. Herpe & D. Saucereau. “Prediction of Flow Separation and Side-loads in Rocket Nozzle Using Large-eddy Simulation”, Int. J. Comp. Fluid Dyn., 2020.

[2] S. Blanchard. “Multi-physics large-eddy simulation of methane oxy-combustion in liquid rocket engines”, PhD Thesis – INP Toulouse, 2021.

[3] O. Cabrit and F. Nicoud. “Direct simulations for wall modeling of multicomponent reacting compressible turbulent flows”, Phy. Fluids, 2009.

[4] M. Cizeron, N. Odier, F. Duchaine, L. Gicquel, and F. Nicoud. “Implementation of a TBLE-based wall model with pressure gradient in a massively parallel LES solver”. ASME Turbo Expo, 2024.

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - daviller@cerfacs.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time!