Effect of Dual Fuel Nozzle Structures on Combustion Flow Field in CRGT Combustor

Three different structures of a new dual fuel nozzle design concept (inner swirl nozzle, double swirl nozzle, and outer swirl nozzle) were developed for the chemically recuperated gas turbine (CRGT) combustor. The combustion flow fields in the combustor with the three nozzles were investigated, respectively, based on the FLUENT simulation. The realizable - model and PDF model were adopted, respectively, for the turbulence flow and nonpremixed reformed gas combustion. The obtained results using these models showed good agreement with experimental results in original oil combustor. The effects of different dual fuel nozzle structures on the flow field, fuel concentration distribution, and temperature distribution in the combustor were simulated and analyzed. Results suggest that the double swirl nozzle and outer swirl nozzle can form a better flow field with obvious central recirculation zone (CRZ), shorten fuel and air mixing distance, and obtain a more uniform outlet temperature distribution, in comparison with the inner swirl nozzle. However, compared with double swirl nozzle, the outer swirl nozzle can result in a better combustion flow field with the high temperature region in the CRZ, which is important to stabilize the flame.