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首页> 外文会议>ASME turbo expo: turbine technical conference and exposition >INTERMITTENCY IN THE DYNAMICS OF TURBULENT COMBUSTORS
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INTERMITTENCY IN THE DYNAMICS OF TURBULENT COMBUSTORS

机译：湍流燃烧器动力学的间歇性

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The dynamic transitions preceding combustion instability and lean blowout were investigated experimentally in a laboratory scale turbulent combustor by systematically varying the flow Reynolds number. We observe that the onset of combustion-driven oscillations is always presaged by intermittent bursts of high-amplitude periodic oscillations that appear in a near random fashion amidst regions of aperiodic, low-amplitude fluctuations. The onset of high-amplitude, combustion-driven oscillations in turbulent combustors thus corresponds to a transition in dynamics from chaos to limit cycle oscillations through a state characterized as intermittency in dynamical systems theory. These excursions to periodic oscillations become last longer in time as operating conditions approach instability and finally the system transitions completely into periodic oscillations. Such intermittent oscillations emerge through the establishment of homoclinic orbits in the phase space of the global system which is composed of hydrodynamic and acoustic subsystems that operate over different time scales. Such intermittent burst oscillations are also observed in the combustor on increasing the Reynolds number further past conditions of combustion instability towards the lean blowout limit. Highspeed 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 intermittent oscillations are thus of prognostic value and can be utilized to provide early warning signals to combustion instability as well as lean blowout.
机译：在实验室规模的湍流燃烧室中，通过系统地改变流量雷诺数，对燃烧不稳定和稀薄爆燃之前的动态过渡进行了实验研究。我们观察到，燃烧驱动振荡的发生总是由高振幅周期性振荡的间歇性突发来预料的，这些突发以几乎随机的方式出现在非周期性，低振幅波动的区域中。因此，湍流燃烧器中高振幅，燃烧驱动的振荡的出现，对应于动力学从混沌到极限循环振荡的过渡过程，该过渡过程以动力学系统理论中的间歇性为特征。随着工作条件趋于不稳定，这些对周期性振荡的偏移在时间上会持续更长的时间，最后系统会完全转变为周期性振荡。这种间歇性振荡是通过在全球系统的相空间中建立同斜轨道而出现的，该系统由在不同时标上运行的流体力学和声学子系统组成。在进一步使雷诺数进一步增加的燃烧不稳定性的条件下，在燃烧器中向贫油吹出极限增加时，也观察到这种间歇性的突发振荡。高速火焰图像显示，在稀薄爆裂之前观察到的间歇状态对应于火焰从钝体唇部的非周期性脱离。因此，这些间歇性振荡具有预后价值，可用于向燃烧不稳定性以及稀薄燃爆提供预警信号。

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