Experimental Study of Flameless Combustion in Gas Turbine Combustors

Abstract

This paper presents experimental data on investigation of novel flameless combustors in application of gas turbine engines at atmospheric conditions. Flameless combustion is characterized by distributed flame and even temperature distribution under the conditions of high preheat air temperature and sufficient large amount of recirculating low oxygen concentration exhaust gas. Extremely low emissions of NOx, CO, and UHC are reported in this paper for flameless combustion in a multiple jets premixed gas turbine combustor and a swirling jet combustor. Measurements on the flame chemiluminescence, CO and NOx emissions, acoustic pressure, temperature field, and velocity field reveal the influence of preheat temperature, inlet air mass flow rate, combustor exhaust nozzle contraction ratio, and combustor chamber diameter on emissions and combustion dynamics. The data indicate that greater air mass flow rate, thus larger pressure drop, promotes the formation of flameless combustion and lower NOx emissions for the same flame temperature. This flameless combustor is in nature a premixed combustion which NOx emission is an exponential function of the flame temperature regardless of different preheated temperature. High preheated temperature and flow rate also helps in forming stable combustion therefore are favorable for flameless combustion. The effects on emissions and combustion dynamics from the combustor exhaust contraction and the combustion chamber diameter are also discussed. (Less)