Abstract

A study was conducted to investigate the flow pattern in a gas turbine combustor using numerical and experimental approaches. The main function of a combustor is to burn the air-fuel mixture then to admit the high energy burnt gases, with uniform and limited temperature, to drive the turbine blades. The gas temperature must not exceed a certain allowable temperature to prevent any damage of the blades. Flow pattern within the combustor has a great effect on the self sustaining flame, mixing of fuel and air, combustion intensity and combustor exit temperature uniformity. For this reason, a radial vaned swirler was used in this study to demonstrate its effect on the flow pattern within the combustor. The radial swirler vanes had an aerodynamically curved profile to allow the incoming axial flow to turn gradually and hence to inhibit the flow separation on the suction side of the vane. Therefore, smooth flow turning, higher tangential and radial-velocity components can be generated at the swirler exit with lower pressure loss. Three swirler vane angles 40°, 50° and 60° corresponding to swirl numbers of 0.35, 0.54 and 1.13 were used to evaluate their effect on the combustor aerodynamics. The results show that the swirl number has a direct proportion relationship with the size and shape of the central recirculation zone as well as the corner recirculation. It is concluded that with the use of 40°, 50° and 60° vane angles swirler, the vortex breakdown phenomena occurs at different intensities and sizes.

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