Investigation of a novel combustion stabilization mechanism and combustion characteristics of a multi-nozzle array model combustor

Abstract

Short and uniformly dispersed flames in multi-nozzle array combustors allow for shorter flue gas residence time, resulting in less NOx emissions at high combustor outlet temperature. A new combustion stabilization mechanism based on high-speed jet induced flue gas recirculation has been utilized in an array model combustor. The stabilization mechanism allows for stable combustion at higher nozzle outlet velocity. The flame stabilization mechanism and combustion characteristics for the model combustor fueled methane have been investigated by using the combination of experiments and numerical simulations. The parameters studied include nozzle outlet velocity, inlet air temperature, and heat loss ratio. The combustion characteristics include NOx/CO emissions and reaction zone distribution. The results show that the flame stabilization mechanism is a result of the combined effects of the inner and outer recirculation zone. Under atmospheric conditions within the adiabatic temperature range from 1500 K to 2100 K, the NOx emissions are less than 20 ppm@15%O2 and the CO emissions are less than 30 ppm@15%O2. As the heat loss ratio decreases, the NOx emissions for the model combustor increase. When the nozzle outlet velocity increases, the lean blowout (LBO) for the model combustor increases. With increasing inlet air temperature, the equivalent ratio range of combustion stability expands. The downstream of the reaction zone is mostly affected by the nozzle outlet velocity and inlet air temperature, while the root of the reaction zone is essentially unaffected due to the role of inner recirculation zone. The unique stabilization mechanism of the multi-nozzle array combustion is beneficial for fuel flexibility.