Impact of swirler sleeve length on outlet temperature distribution of a small gas turbine combustor

Small gas turbine engine combustors hold promising application prospects. Investigating the patterns and mechanisms of how design parameters influence outlet temperature distribution plays a pivotal role in the development of small gas turbine engines with high thrust-to-weight ratios and extended lifespans. Therefore, this study employs high-temperature thermocouple scanning thermometry, particle image velocimetry, planar Mie scattering, and OH* chemiluminescence to examine the impact of varying swirler sleeve lengths on the outlet temperature distribution of a small gas turbine combustor. Both the pilot and main stages of the combustor are fueled with kerosene. Thermocouple test results indicate that increasing the sleeve length leads to an elevation in hot spots at the combustor exit and an expansion of high-temperature regions. In conjunction with optical results, it is revealed that elongating the sleeve enhances and “protects” the fuel–air mixing process within the sleeve, facilitating the formation of high-concentration fuel–air mixtures. Additionally, a longer sleeve stabilizes the heat release zone and recirculation zone further downstream in the combustor, thereby shortening the mixing distance and, to some extent, weakening the heat exchange effects between the mixing/cooling gases and the high-temperature jet core.