Turbulent swirling flames:: Experimental investigation of the flow field and formation of nitrogen oxide

The NO emissions of a 150 kW natural gas (with and without fuel N)burner were shown to be dependent on the geometry of the gas nozzle and the swirl intensity of the combustion air. Numerous detailed in flame measurements were performed in order to understand the local conditions that influence the formation of NO in highly; turbulent swirling flames. It was found, that by controlling the axial fuel gas momentum ill combination with the swirl number, mixing of fuel and air can be influenced. thus reducing NO formation,. Using fuels with chemically fixed nitrogen requires flames with the main heat release under Fuel-rich conditions, leading to type I flames. These flames have the potential to reduce the NO emissions up to;70% compared with premixed Rallies. To minimize thermal NO formation, high-temperature zones with near-stoichiometric mixtures must be avoided, which may be realized by type II flames. Moreover. swirl turned out to be a strong tool for minimizing thermal NO. Under overall fuel-level conditions, higher swirl led to faster mixing of fuel and air, thus lowering the temperature level of the flame and reducing thermal NO emissions. The experiments were performed in cooperation with the German Technische Flammen (TECHFLAM) joint research program. using a standardized combustion chamber and burner. By applying identical experimental setups and different measuring techniques by the TECFLAM partners. accurate and reliable measuring: data were produced on the time-mean and oil the turbulent fluctuation levels.