燃气热水器火排燃烧点火与传火特性数值模拟

Numerical Simulation of Ignition and Fire Propagation Characteristics of Burner Flame Tunnels in a Gas Water Heater

目前燃气热水器只能在特定负荷下点火,开机恒温时间较长,用户使用体验不佳。基于Fluent软件,应用Realizable k-ε湍流模型、涡耗散概念燃烧模型、DO辐射模型及电火花点火模型,采用分段建模的方法对燃气热水器火排燃烧进行了数值模拟,发现火排片内部存在较大旋涡,燃气和一次空气预混效果较好;但在火排片间有明显的低温区,火焰高度差异较大,火焰稳定性较差,影响了任意负荷点火的成功率。进一步对火排燃烧器进行结构优化研究,发现采用两端点火模式,火焰的稳定时间减少32%;安装钝体和侧挡板后,在燃烧室内产生局部回流,提高了燃烧的稳定性,火焰的稳定时间相比原始结构减少16%以上,火焰高度更加均匀。研究结果对燃气热水器火排燃烧器的技术改进提供了参考。

The gas water heater can only be ignited under a specific gas load,and the startup constant temperature time is long,so the user experience is not very good.Based on Fluent software,detailed numerical simulation on flame tunnels combustion in a gas water heater was carried out by piecewise modeling method using Realizable k-εturbulence model,Eddy-Dissipation Concept combustion model,DO radiation model and spark ignition model.It was found that there was large eddies inside the flame tunnel which leads to efficient mixture of gas and primary air.However,there are obvious low temperature zones between flame tunnels,and the flame height is different.And the flame stability is poor,which affects the ignition success rate at arbitrary gas load.The structure optimization of the burner was further studied,and it was found that the stability time of the flame was reduced by 32%after using the both side ignition mode.With the installation of blunt bodies and side baffles,local backflow is generated in the combustor,which improves the combustion stability.The flame stability time is reduced by more than 16%compared with the original structure,and the flame height is more uniform.The research results provide reference for the technical improvement of the burner of a gas water heater.