多点喷射贫预混喷嘴流场及排放特性研究

Based on the development trend of incorporating fuel holes into hollow swirler-vanes and avoiding the auto-ignition and flashback of lean premixed injectors，an original lean premixed injector with multipoint injection and the convergent outlet was proposed. Its fuel holes are located on the swirler-vanes basin and there are a number of cooling holes in its premixing section. The flowfields and emission characteristics of the lean premixed injector were investigated by experiments，and supplementary study on flowfields and fuel/air premixing uniformities were carried out by numerical simulations with the verification of experimental results. The results show that：the main recirculation zone（MRZ）is separated from the injector outlet for a certain distance，which is conducive to the generation of detached flame and avoid the risk of auto-ignition and flashback. The monitoring temperature results of the injector outlet in this paper also confirm that there is no spontaneous combustion and tempering in the injector. The spatial mixing variance（SMV）values at the outlet of the nozzle are all about 4.7% under different pressure conditions，which meets the requirement that SMV of low emission combustor should be less than 5%. The emissions experiment results show that dome equivalence ratio（Φ_dome）of the lean premixed injector，at which its NO_x and CO emissions（@15%O₂）could both meet the emission requirements，ranges from 0.65 to 0.82，and its wide range of Φ_dome can reduce the number of stages used in full ring combustor. In addition，when Φ_dome is lower than 0.70，the lean premixed injector is capable of achieving NO_x emissions below 1.0×10^-5（@15%O₂）. Therefore，the original lean premixed injector proposed in this paper could meet the stringent emission standards of industrial gas turbine.