Flame/wall interaction and maximum wall heat fluxes in diffusion burners

Determining maximum wall heat fluxes in diffusion burners (rocket engines, diesel engines, or gas turbines) is a critical question for many combustion chambers. These fluxes are often due to flame/wall interaction (FWI) phenomena. This interaction may be due to either premixed or diffusion flamelets impinging on walls. Possible FWI configurations in diffusion burners are analyzed, and a proper laminar configuration for FWI studies (a diffusion flame impinging on a wall in a stagnation point flow) is identified. This case is studied for a variety of strain rates in terms of minimum distances between flame and wall and maximum wall heat fluxes. Results show that diffusion flames interacting with walls can generate heat fluxes which are larger than a premixed stoichiometric flame and that these mechanisms must be accounted for to predict wall heat fluxes in real burners.