: The present work is focused to characterize numerically the merged and non-merged flame emanating from the cavities in downstream of twin cavity Annular Trapped Vortex Combustor (ATVC).The isotherm corresponding to the auto-ignition temperature is used to locate the merging point of the flame in the mainstream region along the combustor length. In present study, the cavity flame is said to be merged only if this isotherm corresponding to self-ignition temperature of methane is located within 20 percentage of the combustor length from aft wall of cavities. It is interesting to note that on increasing the power loading parameter (PLP) in mainstream for a constant power loading parameter ratio (outer to inner cavity), the merging point gets shifted towards the cavity aft-wall. This leads to the reduction of combustor length and subsequent reduction in overall weight of the gas turbine engine.