A Non-Adiabatic Flamelet Approach for Non-Premixed O2-CH4 Combustion

Abstract

Numerical simulations of turbulent reactive flows are challenging due to the stiffness of chemical rate equations, depending on the number of species, reactions and time scales involved. A possible solution to speed-up the calculations is the use of tabulated manifolds for the thermo-chemical properties of the flame. In order to capture the effects of the flame-wall interactions, the pre-processed library shall include a parameter which accounts for heat losses. The generation of a non-adiabatic flamelet manifold is presented in this work, where the enthalpy defect experienced in proximity of the wall is included in the flamelet generation. A laminar simulation of a non-premixed methane/oxygen flame at elevated pressure is run to validate the manifold. The main differences to the frozen chemistry tabulation method previously in use are then underlined and referred to a finite rate chemistry case. Finally, a first assessment of the models was performed, based on a single-injector rocket chamber test case. The wall heat flux is compared with the available experimental results.

Subgrid Turbulent Flux Models for Large Eddy Simulations of Diffusion Flames in Space Propulsion

“…Traditionally, Reynolds Averaged Navier-Stokes (RANS) solvers have been extensively used in industry due to their low computational cost. In methane thrust chambers, multiple researchers have used this methodology for both the combustion chamber [10][11][12] and the cooling system [13][14][15][16][17]. The most relevant handicap of this approach is the suppression of transient behavior, which excessively restricts the degrees of freedom of the turbulent flow dynamics.…”