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为研究燃烧过程中的热声振动特性,搭建了Rijke型预混燃烧器热声振动特性试验台架,并进行了化学当量Ф为0.8、1.0和1.2的三组试验研究。Rijke型预混燃烧器为直径40 mm,管长1066 mm的不锈钢圆管,下端封闭,上端开口。致密堇青石材质的多孔介质稳燃体位于燃烧器四分之一管长处,甲烷与空气的预混气体在稳燃体上方燃烧。试验获得的燃烧温度位于611 K—943 K之间;热声振动频率在440 Hz—476 Hz之间;热声振动声压级位于131 dB—146 dB之间。试验发现,Rijke型预混燃烧器的燃烧温度在同一燃烧功率下基本一致,不受化学当量比的影响。热声振动频率随燃烧功率的增加轻微上升,不同化学当量比下振动频率的变化幅度不相同,贫燃和富燃时频率随燃烧功率的增加有较大的增加,且贫燃大燃烧功率时出现了低频大振幅振动与高频振动并存的现象。热声振动强度强烈依赖于燃烧功率和化学当量比,同一燃烧功率不同化学当量下的热声振动强度相差可达50%。
In order to study the thermoacoustic vibration characteristics during combustion, a thermoacoustic vibration test rig for Rijke type pre-mix burners was set up and three groups of experiments with equivalent Ф of 0.8, 1.0 and 1.2 were carried out. The Rijke premix burner is a stainless steel tube 40 mm in diameter and 1066 mm in length with a closed lower end and an open upper end. The tight cordierite porous material is located at a quarter of the length of the combustor and the premixed gas of methane and air is combusted over the steady-state fuel. The experimental combustion temperature was between 611 K and 943 K, the thermal acoustic vibration frequency was between 440 Hz and 476 Hz, and the thermal acoustic vibration sound pressure level was between 131 dB and 146 dB. It was found that the combustion temperature of the Rijke premix burner was basically the same at the same combustion power without being affected by the stoichiometric ratio. The frequency of thermoacoustic vibration increases slightly with the increase of combustion power. The variation of vibration frequency at different stoichiometric ratios is different. The frequencies of lean and rich combustion increase with the increase of combustion power, Appeared low-frequency large-amplitude vibration and high-frequency vibration coexist phenomenon. The intensity of thermoacoustic vibration strongly depends on the combustion power and the stoichiometric ratio, and the difference between thermoacoustic vibration intensities at different stoichiometries of the same combustion power is up to 50%.