Research on Effect of Fuel-staging Ratio on Low-power Operation Performance in a Centrally-staged Combustor
The fuel distribution strategy significantly influences the combustion organization of low-emis-sion combustors.To explore the effect of pilot fuel-staging ratio on the performance of centrally-staged combustors under low-power operating conditions,numerical simulations were conducted in a single-sec-tor centrally-staged combustor using five different fuel distribution schemes,under 0.017 constant fuel-air ratio.The effects of various pilot fuel-staging ratios on the combustion flow field characteristics,tempera-ture distribution,fuel spatial distribution,flame structure,and emission characteristics were analyzed.Furthermore,the comprehensive performance of the combustor was evaluated.The research results indi-cate that variations in the pilot fuel-staging ratio have no significant impact on the combustion flow field structure and velocity distribution under the low-power operation condition.Reducing the proportion of pi-lot fuel distribution causes the area of high-temperature zone inside combustor to initially shrink and then enlarge,while the distance between high-temperature zone boundary and pilot nozzle simultaneously shortens.Concurrently,the pilot flame front shifts toward the swirler along combustor axis,while the front position and opening angle of primary flame remain essentially unchanged.The pilot fuel-staging ra-tio decreases from 1 to 0.2,resulting in a reduction in combustor combustion efficiency from 99.87％to 99.71％and an increase in CO emissions from 68.12 × 10-6 to 190.32 × 10-6.The outlet temperature distribution factor(OTDF)initially decreases and then increases,reaching a minimum value of 21.75％at a pilot fuel-staging ratio of 0.6.
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