摘要
研究了一个采用脉动供燃料燃烧方式的射流扩散火焰 ,利用直接摄像技术观察分析了在不同工况参数下的火焰特征及其变化规律 ,包括富燃时间份额、平均雷诺数和管道连接状况等 ,分析了各参数的影响和共振工况下的火焰特征。结果表明 ,富燃时间份额在 70 %～ 90 %范围内火焰呈现较规则的贫富燃交替结构 ,在共振频率时更加清晰 ,70 %～80 %时火焰长度最长 ,交替结构最规则 ;在更低的富燃时间份额时 ,共振频率下火焰根部出现崩溃性混合和湍流且火焰升起 ,其值愈低湍动愈强 ,在其它频率下保持附着 ,而长度变短 ,在 5 5 %～ 6 0 %时长度最短。管道连接状况也影响火焰脉动特性。共振频率下 ,平均雷诺数增大火焰可在较高富燃时间份额下升起 。
A jet-flow diffusion flame based on the adoption of a pulsating fuel-feed combustion mode is investigated. By making use of a direct photographing technique the characteristics and variation mechanism of the flame are observed and analyzed under various operating conditions and parameters. They include: fuel-rich combustion-time share, average Reynolds number and pipe connecting conditions, etc. The impact of various parameters and the flame characteristics under resonant operating conditions are also analyzed. It was found that with the fuel-rich combustion-time share in the range of 70% -90% the flame would assume a more or less regular fuel-rich and fuel-lean alternative structure with a clearer picture being observed during resonant frequencies. At a duty cycle of 70% - 80% the flame has a maximum length and the alternative structure assumes a most regular form. At a still lower duty cycle of fuel-rich combustion-time share there emerged under a resonant frequency a collapsed mixing and turbulent flow at the root of the flame accompanied by a flame lift-off. The lower the resonant frequency, the stronger the turbulence. At other frequency values the flame remains attached and has a shorter length with the shortest length appearing at 50% to 60% of duty cycle. The condition of piping connection can also influence the pulsating characteristics of the flame. Under resonant frequencies and with an increase in average Reynolds number the flame may lift off at a relatively high fuel-rich combustion-time share while under other frequencies the flame will remain attached all the time.
出处
《热能动力工程》
CAS
CSCD
北大核心
2004年第4期372-375,415,共5页
Journal of Engineering for Thermal Energy and Power
关键词
脉动供燃料燃烧
低NOX燃烧
火焰特征
交替火焰结构
combustion with a pulsating fuel feed, low NO_x combustion, flame characteristics, flame alternative structure.
