CFD Analysis of Afterburner with Convergent–Divergent Nozzle for Various Air–Fuel Ratios

Military jet aircraft fitted with afterburner gets additional thrust in extraordinary circumstances like combat. The jet aircraft must work in wide-ranging temperatures with different air–fuel ratios under varying circumstances. However, many researchers observed that jet aircraft operating with the lean air–fuel configuration is associated with instabilities, which is not under the scope of this paper. In the present paper, the afterburner, consisting of a convergent–divergent nozzle and essential components, is simulated for varying air–fuel ratios from 16 to 45 to check the effect of the increase in the fuel supply. Accordingly, the afterburner is modeled with liner, diffuser, V-gutter, fuel manifolds, and casing with a convergent–divergent nozzle. Computational fluid dynamics analysis is carried out with the help of Ansys Fluent® using SIMPLE algorithm, realizable k − ε turbulence model, energy equation, species transport, and discrete phase with finite-rate/eddy-dissipation model for combustion. The simulations were carried out for various air–fuel ratios 16, 19, 23, 30, and 45. Out of these different afterburner models, the afterburner with the minimum air–fuel ratio of 16 is found to attain the maximum velocity and maximum thrust. These results also match the experimental results of Useller et al. (Influence of combustion chamber length on afterburner performance. Lewis Flight Propuslion Laboratory, Cleveland, 1954, [1]).