摘要
为了探索高温伴流射流(jet in hot coflow,JHC)无焰燃烧(moderate or intense low oxygen dilution,MILD)建立的条件,利用数值模拟的方法研究了JHC火焰在不同伴流温度与伴流氧气质量分数下的火焰特性。使用商业CFD软件ANSYS FLUENT 15.0,开展稳态RANS(Reynolds averaged Navier-Stokes)模拟,湍流模型采用标准κ-ε双方程模型,化学反应采用DRM 22详细反应机理,湍流与化学反应的相互作用采用涡耗散概念(EDC)模型。模拟结果表明:提高伴流温度加强了火焰内部的传热过程;降低氧气浓度减小了化学反应释放的热量,显著降低了火焰亮度,使火焰锋面变得模糊,氧气浓度在转变燃烧状态时起到更加明显的作用;燃料主射流的初始速度决定了反应区域的湍流时间尺度,伴流温度通过影响湍流时间尺度影响宏观燃烧状态;降低伴流氧气浓度增加了化学反应时间尺度,使宏观燃烧更均匀温和,燃烧模式的转变过程更加规律可控。
In order to study the establishment conditions of MILD(Moderate or Intense Low-oxygen Dilution)combustion of H2/CH4 Jet-in-Hot-Coflow(JHC)flame,numerical simulation method was used to investigate the combustion characteristics of the JHC flame under different operating conditions of coflow temperature and coflow oxygen concentration.The commercial CFD(Computational Fluid Dynamics)software ANSYS FLUENT 15.0 was employed with the steady-state RANS(Reynolds Averaged Navier-Stokes)model and detailed reaction mechanism DRM22,and EDC(Eddy Dissipation Concept)combustion model was selected.The results indicated that the heat transfer process inside the flame is enhanced when temperature of the coflow increases;as the oxygen concentration of the coflow decreases,the heat release of chemical reaction is constrained and the brightness of the flame is reduced significantly while the flame front gets blurred;the oxygen concentration plays a more important role in the combustion regime transformation;the velocity of the main jet determines the turbulent time scale of the reaction zone while the coflow temperature affects the combustion regime by affecting the turbulent time scale;when the oxygen concentration decreases,the time scale of the chemical reaction increases,and the macroscopic combustion becomes more uniform and milder while the transformation of the combustion regime is more controllable.
作者
王奔
万凯迪
何勇
朱燕群
王智化
岑可法
WANG Ben;WAN Kai-di;HE Yong;ZHU Yan-qun;WANG Zhi-hua;CEN Ke-fa(State Key Laboratory of Clean Energ Utilization,Zhejiang University,Hangzhou 310027,China)
出处
《能源工程》
2020年第5期1-9,共9页
Energy Engineering
基金
国家重点研发计划资助项目(2018YFB1502900)。
