特征参数对微混喷嘴内燃料与空气混合均匀性影响

Due to the small size, large number and non-swirl structure of the micromix nozzle, the micromix combustor structure may form a new design criterion. In order to explore the optimization method of the mixing characteristics inside the micromix nozzle, the characteristic parameters such as Reynolds number inside the nozzle, the relative premixed length and the jet momentum ratio were extracted and the effect of the characteristic parameters on the fuel/ air mixing characteristics were studied by Large-eddy simulation model. The results show that, with the increase of premixed distance, the mixing space is expanded, and the mixing characteristics obviously improves. Moreover, the fuel-air mixture is more intense under the large jet momentum ratio, and the mixing quality also show an upward trend. However, fuel inlet velocity has little impact on the mixing performance of the nozzle, and when the Reynolds number is above 1×10⁵, the flow state reaches the second self-modeling region in the nozzle, and the mixing uniformity is no longer related to Reynolds number. Further, the mixing uniformity of the nozzle is fitted by these characteristic parameters, the fitting formula could accurately predict the mixing uniformity while the equivalence ratio is in the range of 0.5—1.0, the Reynolds number is above 1×10⁵ and the inlet air temperature is in the range of 18—818 ℃. The fitting formula can be used to preliminarily calculate the mixing characteristics of the micromix nozzle and provide reference experience for the nozzle structural design.