An experimental study on the high frequency oscillatory combustion in tubular flame burners
An experimental study on the high frequency oscillatory combustion in tubular flame burners
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DOI：
10.1016/j.combustflame.2014.01.027
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发表时间：
2014-08
影响因子：
4.4
通讯作者：
D. Shimokuri;Yousuke Shiraga;K. Ishii;H. Toh;S. Ishizuka
中科院分区：
文献类型：
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作者：
D. Shimokuri;Yousuke Shiraga;K. Ishii;H. Toh;S. Ishizuka
在本研究中，采用大尺寸8- In和12-in实验研究了管式火焰燃烧器的高频振荡燃烧。直径管式火焰燃烧器。确定了高频振荡燃烧的条件，测量了压力波动，并对其进行了频谱分析。结果表明：该方法可以建立光滑的层流管状火焰，但在8- in和12-in处会发出高频燃烧声。当风量分别超过650和1200 m3/h时，燃烧器。压力脉动测量和频谱分析表明，在高频振荡过程中，高压脉动同时发生。用高速摄像机拍摄了火焰图像。在振荡过程中，火焰表面出现了明显的波纹，对称性被破坏。假设管式火焰燃烧器是一个简单的管，利用圆柱腔内声共振的基本理论确定了燃烧器的固有频率，并将光谱中的实验峰值频率与固有频率进行了比较。结果表明，两种燃烧器的高频振荡均为切向/径向型声学谐振振荡。进一步发现，具有非对称结构的切向第一振型先于高阶振型，表明该振型主导了高频振荡的发生。为了验证切向第一模态振荡的发生，用安装在相对位置的两个压力传感器测量了压力波动。结果表明，振荡相位相差180°，结构不对称，证实了切向第一振型的存在。
In this study, high frequency oscillatory combustion in tubular flame burner was experimentally investigated using large scale 8- and 12-in. diameter tubular flame burners. The conditions for the high frequency oscillatory combustion were determined, and the pressure fluctuations were measured, on which spectral analyses were made. The results showed that a smooth laminar tubular flame could be established, however, high frequency combustion sound was emitted from the 8- and 12-in. burners when the air flow rates exceeded 650 and 1200 m3/h, respectively. Pressure fluctuation measurements and spectral analyses showed that high frequency pressure fluctuations occurred simultaneously during the high frequency oscillation. The flame images were also obtained with a high speed video camera. The flame surface was found to be notably corrugated and the symmetry was broken during the oscillation. By assuming that the tubular flame burner is a simple tube, the natural frequencies of the burners were determined using the fundamental theory of the acoustic resonance in a cylindrical cavity, and the experimental peak frequencies in the spectra were compared with the natural frequencies. As a result, it was found that the high frequency oscillations in both the burners were identified as the tangential/radial mode acoustic resonant oscillations. It was further found that the tangential first mode of oscillation, which had an asymmetric structure, preceded the higher modes of oscillation which indicated that the mode dominated the occurrence of the high frequency oscillation. To verify the occurrence of the tangential first mode oscillation, the pressure fluctuations were measured with two pressure sensors installed at opposed locations. The results showed that the phase of the oscillation was 180° difference, and the asymmetric structure confirmed the occurrence of the tangential first mode of oscillation.