Numerical investigation of turbulent flame-vortex interaction in premixed cavity stabilized flames

Abstract

The combustion dynamics of a mixture of ethylene and air in a cavity flameholder are examined using high-resolution numerical simulations. The simulations are performed using both laminar and turbulent inflow boundary conditions to characterize the effects freestream turbulence on the flame-vortex interactions within the combustor. Experimental test results are utilized to validate the simulation's ability to capture the relevant flow and flame behavior. The turbulence intensity is shown to influence the structure of the flow field by creating a more dominant primary vortex within the combustor and decreasing the shear layer reattachment length. The integral length scales and energy spectra are calculated throughout the domain and show that the flow is driven by smaller turbulent eddies within the ramp region of the combustor. The flame-vortex interaction is further examined and revealed to cause an instability forming in the combustor under both laminar and turbulent conditions. The instability is confirmed by examining the pressure fluctuations within the combustor and it is demonstrated that the time scale of the pressure fluctuations corresponds to the frequency of the vortex shedding from the ramp wall.