Analysis of combustion noise of a turbulent premixed slot jet flame
Analysis of combustion noise of a turbulent premixed slot jet flame
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DOI：
10.1016/j.combustflame.2016.08.001
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发表时间：
2017
影响因子：
4.4
通讯作者：
S. Schlimpert;S. Koh;K. Pausch;M. Meinke;W. Schröder
中科院分区：
文献类型：
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作者：
S. Schlimpert;S. Koh;K. Pausch;M. Meinke;W. Schröder
采用混合分析方法对湍流流场与预混狭缝火焰相互作用产生的声辐射进行了数值研究。不同的气体膨胀比和Markstein长度的影响进行了研究。声学火焰响应函数和声源项确定了对热释放波动的总体火焰响应。通过空间和频谱声源项分布和频谱火焰前沿响应研究计算声音发出的位置。缝隙射流的火焰声响应与圆形射流的火焰声响应相似。从目前的结果和文献数据可以推测，只要火焰经历湍流火焰-流动相互作用，典型的声压和放热趋势导致低频区（St <20）的声学火焰响应趋势为α St 2，St <20的声学火焰响应趋势为平台区β St 0。在含能区（α St 2），声学声是由局部放热波动产生的，而局部放热波动是由几个平均火焰前缘位置处的光谱火焰前缘响应决定的。声源项取决于气体膨胀和剪切层效应引起的火焰前锋运动。在火焰底部，由于增加的涡-火焰相互作用，火焰袋的生成在减小气体膨胀比时增强。在火焰尖端，火焰袋的产生增加，在高温比由于流体动力学不稳定性的影响。火焰前缘运动学通过火焰-流动相互作用影响声源项，并导致降低气体膨胀比的火焰响应幅度较低。
The sound generation due to the interaction between the turbulent flow field and a premixed slot flame is numerically studied by a hybrid analysis. The impact of varying gas expansion ratios and Markstein lengths is investigated. The acoustic flame response function and the acoustic source terms determine the overall flame response to heat release fluctuations. The location where sound is emitted is computed by the spatial and spectral acoustic source term distribution and a spectral flame front response study. The acoustic flame response of the slot jets is similar to that of round jets. From the current results and data from the literature it is suspected that as long as the flame undergoes a turbulent flame–flow interaction a typical acoustic pressure and heat release trend leads to an acoustic flame response trend ofαSt2in the low frequency region (St≲ 20) and a plateau regionβSt0forSt≳ 20. In the energy containing region (αSt2), the acoustic sound is produced by local heat release fluctuations determined by the spectral flame front response at several mean flame front locations. The acoustic source terms depend on the gas expansion and shear layer effect induced by the flame front kinematics. At the flame base, flame pocket generation is enhanced at decreasing gas expansion ratio due to the increased vortex–flame interaction. At the flame tip, flame pocket generation is increased at high temperature ratios due to the hydrodynamic instability effect. The flame front kinematics affects the acoustic source terms by the flame–flow interaction and leads to a lower magnitude of flame response for decreasing gas expansion ratios.