Two afterburner full scaled models one with a standard V-gutter and second with a modified V-gutter were modelled in SolidWorks^®. The other important components of the afterburner include diffuser with struts, fuel manifolds, liner with screech & cooling holes, convergent divergent nozzle and casing. In each of this model the combustion chamber length is maintained as 5 feet. Extended domain with three times the throat diameter in axial direction and two times the throat diameter in the radial direction had also been considered for the analysis. The computational fluid flow analysis has been carried out after the import of the model into ANSYS^®Fluent not only to obtain the variation of important parameters like velocity, temperature, pressure and density, but also enable to predict the combustion instabilities after the acoustic analysis, which is not presented in this paper. The 60° sector of each of this full-scaled model was used for analysis. For performing the numerical calculations SIMPLE algorithm, realizable k-ε turbulence model, species transport, discrete phase model with finite rate/eddy dissipation model for combustion, were employed.