氢燃料微混燃烧器燃烧特性研究

Study on Combustion Characterization of Hydrogen Fuel Micro Mixing Burner

针对带中心钝体的四喷嘴微混燃烧器,运用ANSYS FLUENT软件,采用热态小火焰生成流形的方法对燃烧器模型进行数值模拟,并与实验研究相结合,研究了甲烷/氢气混合燃料(体积组分40%CH_(4)-60%H_(2))微混燃烧条件下的燃/空掺混,流场、温度场、火焰形态及污染物排放等基础燃烧特性。研究结果表明:微混燃烧器采用空气和燃料径向进气的结构有利于燃/空掺混,在燃烧器出口的掺混均匀性指数达到0.959;燃烧器钝体结构处存在较明显的小型中心回流区,有助于火焰稳定;当量比在0.4~0.8范围内,火焰根部稳定附着在微混喷嘴的出口,火焰彼此相互独立,实验中燃烧器火焰形态与仿真OH^(*)场分布基本一致;绝热火焰温度在1500~2050 K范围内,模型燃烧室出口NO_(x)排放浓度均低于16×10^(-6),CO排放浓度均低于11×10^(-6),表明该微混燃烧器的污染物排放水平较低且燃烧效率极高。

Taking the four-nozzle micro mixing burner with a center blunt body as the object,the combustor model was numerically simulated by using ANSYS FLUENT software and the flamelet-generated maniflod method under thermal state,which was combined with experimental studies to investigate the fundamental combustion characteristics of micro mixing burner of methane-hydrogen mixed fuels with volume fraction of 40% CH_(4) and 60% H_2,such as fuel-air mixing,flow field,temperature field,flame morphology and pollutant emission.The results show that the structure of the micro mixing burner with radial air and fuel intake facilitates fuel-air mixing,and the doping uniformity index at the burner outlet reaches 0.959;there exists a small and obvious central reflux zone at the burner blunt body structure,which contributes to the flame stabilization;in the range of equivalence ratio from 0.4 to 0.8,the flame roots stably adhere to the outlet of micro mixing nozzle,which are independent of each other,and the burner flame morphology photos in the experiment are basically consistent with the simulated OH~* field distribution;in the range of adiabatic flame temperature from 1 500 to 2 050 K,the NO_(x) emissions at the model combustion chamber outlet are all lower than 16×10~(-6),and the CO emissions are all lower than 11×10~(-6),which indicates that the micro mixing burner has a low pollutant emission level and a very high combustion efficiency.