Intermittency as a Transition State in Combustor Dynamics: An Explanation for Flame Dynamics Near Lean Blowout
Intermittency as a Transition State in Combustor Dynamics: An Explanation for Flame Dynamics Near Lean Blowout
复制标题
间歇性作为燃烧室动力学中的过渡状态：对近稀薄井喷火焰动力学的解释
DOI：
10.1080/00102202.2015.1066339
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发表时间：
2015
影响因子：
1.9
通讯作者：
R. Sujith
中科院分区：
文献类型：
--
作者：
V. Nair;R. Sujith
在实验室尺度的湍流燃烧室中，通过系统地改变流动雷诺数，研究了贫油喷出前的动态转变。以前对燃烧室动力学的研究表明，燃烧驱动的大幅度振荡的开始，有时预示着高幅度周期性压力脉动的间歇性爆发。这些间歇性爆发以近乎随机的方式出现在非周期性低幅度起伏的区域中，前提是基本的流场是湍流的。在目前的研究中，我们发现在接近贫燃极限的燃烧室中也观察到了间歇性的猝发振荡。我们证明了这种间歇振荡是通过在压力振荡的相空间中建立同宿轨道而出现的。这种轨道的形成表明流体动力学和声学子系统之间相互作用的复杂性，它们在一系列不同的时间尺度上运行。高速火焰图像显示，在倾斜喷出之前观察到的间歇状态对应于火焰从钝体嘴唇上非周期性地脱离。这些发现与文献中关于可能间歇性状态的其他报告一致。
The dynamic transitions preceding lean blowout were investigated experimentally in a laboratory scale turbulent combustor by systematically varying the flow Reynolds number . Previous studies on combustor dynamics have shown that the onset of large-amplitude, combustion-driven oscillations is, at times, presaged by intermittent bursts of high-amplitude periodic pressure pulsations. These intermittent bursts appear in a near random fashion amidst regions of aperiodic low-amplitude fluctuations, provided the underlying flow-field is turbulent. In the present study, we show that intermittent burst oscillations are also observed in combustors close to the lean blowout limit. We show that such intermittent oscillations emerge through the establishment of homoclinic orbits in the phase space of pressure oscillations. The formation of such orbits points to the complex nature of the interaction between the hydrodynamics and acoustic subsystems, which operate over a range of different time scales. High-speed flame images reveal that the intermittent states observed prior to lean blowout correspond to aperiodic detachment of the flame from the bluff-body lip. These findings are consistent with other reports of possibly intermittent states in the literature.