Effect of swirler geometry on the outlet temperature profile performance of a model gas turbine combustor

Abstract

This study investigates the impact of swirl numbers, swirl direction combinations, and recirculation zone geometries on outlet temperature distribution and combustion efficiency through numerical simulations using the standard k-ε turbulence model. The research focuses on how variations in swirl numbers and directions affect the formation of high-temperature zones, recirculation patterns, and overall combustor performance. The simulations demonstrate that an increase in the swirl number of the third swirler results in a shift of the local high-temperature zone towards the dome, whereas higher swirl numbers of the first and second swirlers amplify the temperature peak. When the second and third swirlers rotate in the same direction, recirculation occurs at the outlet, moving the high-temperature zone closer to the exit. A decrease in the number of fuel supply nozzles leads to a higher outlet temperature distribution factor (OTDF), while an increase in the number of nozzles enhances temperature distribution. The central recirculation zone significantly influences the outlet temperature of the combustor, with an optimal cold-state length-to-height ratio (L/H)_n of approximately 1.2 and a reactive-state (L/H)_r, of 2 improving temperature distribution. As the ratio decreases from 1.771 to 1.289, the OTDF decreases from 0.41 to 0.24. Higher swirl numbers increase combustion efficiency, with Case3 achieving 99.86%. Insufficient fuel–air mixing under low swirl conditions leads to incomplete combustion, whereas higher swirl numbers promote better mixing and efficiency. These findings provide a foundation for further advancements in high-performance aeroengine combustor design.