LES of Combustion Dynamics in an Ethylene-Hydrogen-Air Ramjet

• A combustion Large Eddy Simulation (LES) is used to examine the flow, mixing, fuel-injection and combustion dynamics of a ramjet combustor with a cavity flame holder. The combustor is a running 50/50, in mole, ethylene/hydrogen fuel mixture. A direct-connect facility dual-mode ramjet/scramjet combustor presents the target case, with in the literature available experimental data is used in the present study for validation of the current LES results. Experimental data for time-averaged chemiluminescence, represented by the CH* signal, and CH-PLIF and OH-PLIF, are used to validate the LES. The LES, using a compact 66-step reaction mechanism for the ethylene/hydrogen/air combustion, predicts a highly dynamic combustion behavior, where the flame oscillates between longer sequences in a cavity stabilized state and shorter ones with a jet-wake stabilized state. A volume averaging in cross-section slabs along the combustor length, plotted over time, is used to further examine and visualize the dynamic combustion and the effects of the dynamics on the temperature, pressure, heat release and axial velocity. Such cross-section slabs, and constant volume simulations, is used to further investigate the predictive effect of the accumulation of H2O2 on the combustion dynamics and the sudden increases in flame size associated with the dynamic flame behavior.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik -- Strömningsmekanik och akustik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering -- Fluid Mechanics and Acoustics (hsv//eng)

Keyword

combustion dynamics

ethylene

hydrogen

LES

ramjet

Publication and Content Type

kon (subject category)

ref (subject category)