CFD study of isothermal flow in an afterburner system

This paper focuses a detailed numerical prediction of non-reacting flow analysis in a practical 1/3 scaled model gas turbine afterburner system. The analysis is performed using SIMPLE algorithm in a body-fitted multi-block grid using STAR-CD software. The turbulence is simulated using standard k-ε model. The validation of software is carried out in a afterburner model by comparing axial, radial and circumferential velocities at various axial locations. The agreement between the prediction and experimental data are quite reasonable. The analysis is extended to the flow in a practical afterburner system. The afterburner system consists of an annular diffuser, a complex three-dimensional flame stabilizer, a liner with chute, screech and cooling rings holes and a convergent nozzle. The wall static pressures are compared with experimental data obtained from rig results for both core and bypass casing. The agreement between CFD prediction and experimental data arc in close agreement. The predicted length of the re-circulation zone of the lower radial gutter is larger (2.7 times width of the gutter) than upper radial gutter, which is about 2.3 times width. This is due to combined effect of annular diffuser and lower radial gutter. But the length of the re-circulation zone of the annular ring is slightly less than (0.94 times) the width of the v-gutter. The effect of different mass flow rates on the afterburner performance is also evaluated and it is observed that mass flow rate does not affect the re-circulation zone characteristics. An increase of 20% in mass flow rate increases the exit nozzle velocity by 35%.