Fuel injection at two locations in a combustor using premixed, partially pre-mixed and non-premixed schemes has been explored for improved distributed combustion. The effect of dual location fuel injection to the combustor is examined and the results compared from single fuel injection. Focus of dual and single injection scheme was on enhancing reaction zone uniformity in the combustor. A cylindrical combustor at a combustion intensity of 36MW/m3.atm and heat load of 6.25 kW was used. Three different schemes of dual location fuel injection with different proportions of fuel injected from each injector were investigated using methane as the fuel. The role of fuel distribution between the two injection ports using constant air flow rate to the combustor at room temperature was examined on reaction zone distribution and pollutants emission. Three different equivalence ratios of 0.6, 0.7 and 0.8 were examined with different fuel distributions between the two injectors to the combustor at a constant overall thermal load. The results showed lower emission with dual location fuel injection as compared to single location. Dual location fuel injection showed 48% NO reduction with 90% of the total fuel from injector 1 while only 13% reduction was achieved with 80% of the fuel injection from this location. . OH* Chemiluminescene intensity distribution within the combustor showed that under favorable fuel injection condition, the reaction zone shifted downstream to allow longer fuel mixture preparation time prior to ignition. The longer mixing time resulted in improved mixture preparation and lower emissions. The OH* Chemiluminescene intensity distribution with fuel introduced through two injectors showed improved OH* distribution in the combustor. Improved mixture preparation enhanced reaction distribution in the combustor and lower emission.

The influence of oxygen enriched air-methane flame under non-premixed and premixed fuel-lean combustion conditions is examined with focus on the emission of NO and CO, combustor exit temperature (T exit ), and distribution of OH * chemiluminescence intensity. A cylindrical combustor was used at combustion intensity of 36MW/m 3 .atm and heat load of 6.25 kW. Results are also reported with normal air (21% oxygen). Oxygen enrichment provided stable combustion operation at lower equivalence ratios than normal air and also reduced CO emission. Increase in oxygen concentration from 21% to 25% and 30% increased the NO and decreased CO emissions at all equivalence ratios examined. Using 30% O 2 enriched air in premixed case showed NO emissions of 11.4 ppm and 4.6 ppm at equivalence ratios of 0.5 and 0.4, respectively. Oxygen enrichment also reduced CO emission to 38 ppm at equivalence ratio of 0.5. Operating the combustor with normal air at these equivalence ratios resulted in unstable combustion. OH * Chemiluminescence revealed increased chemiluminescence intensity with the reaction zone to shift upstream at increased oxygen concentration. The exhaust temperature of the combustor increased with oxygen enrichment leading to lower CO concentration and increased combustion efficiency. The oxidizer injected at higher velocities mitigated the impact of reaction zone to move upstream that helped to reduce significantly both the NO and CO emission specifically under non-premixed combustion.