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旋流燃烧器内部流动复杂,涡系丰富,为研究燃烧功率对其热声不稳定特性的影响,搭建了旋流燃烧器热声不稳定试验台架。旋流燃烧器工作在常压下,其燃料风喷口直径为2mm,通过切向进气方式引入旋转二次风,燃烧室直径为48mm,高度为600mm。试验测量了燃烧功率为2.8~7.1kW的CH4/空气火焰的脉动压力和温度分布,旋流强度约为0.58。试验结果表明:旋流燃烧器热声不稳定的共振频率介于251~273Hz之间,声压级Lp与燃烧功率Pc有线性关系:Lp=112.099+3.537Pc。采用联合时频分析方法研究了压力脉动波形,发现旋流燃烧器内的压力脉动介于时不变性质与时变性质之间,其短时频谱的主峰频率和振幅均为时间的函数,但主峰频率的变化范围较小;当燃烧功率为6.2kW时,最大的短时声压级可达153dB。
In order to study the influence of combustion power on the thermoacoustic instability characteristics of the swirl burner, the flow inside the swirl burner is complex, and the vortex system is rich. A thermoacoustic instability test bench for the swirl burner is set up. Swirl burner work under atmospheric pressure, the fuel nozzle diameter of 2mm, through the introduction of tangential air into the rotating secondary air, the combustion chamber diameter of 48mm, a height of 600mm. The pulsating pressure and temperature distribution of CH4 / air flame with combustion power of 2.8 ~ 7.1kW were measured. The swirling intensity was about 0.58. The experimental results show that the thermoacoustic instability of the cyclone burner is between 251 and 273 Hz, and the linear relationship between the sound pressure level Lp and the combustion power Pc is Lp = 112.099 + 3.537Pc. The pressure pulsation waveforms are studied by the joint time-frequency analysis method. It is found that the pressure pulsation in the swirling burner is between time-invariant and time-varying nature. The frequency and amplitude of the main peak of the short-time spectrum are time functions. The main peak frequency range is small; when the combustion power is 6.2kW, the maximum short-term sound pressure level up to 153dB.