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首页> 外文会议>International Congress on Sound and Vibration >FLOW - ACOUSTIC - FLAME INTERACTION DURING THE TRANSITION TO THERMOACOUSTIC INSTABILITY IN A TURBULENT LIFTED JET FLAME COMBUSTOR
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FLOW - ACOUSTIC - FLAME INTERACTION DURING THE TRANSITION TO THERMOACOUSTIC INSTABILITY IN A TURBULENT LIFTED JET FLAME COMBUSTOR

机译：流动 - 声火焰相互作用在湍流升降喷射火焰燃烧器中的热声不稳定性期间

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Transition to thermoacoustic instability from combustion noise via intermittency occurs in a turbulent lifted jet flame combustor when the position of burner inside a confinement is changed. The role of the coupling of flame, flow and duct acoustics leading to transition from combustion noise to thermoacoustic instability is captured with the simultaneous measurement of acoustic pressure, CH~* chemiluminescence images of the flame and Mie scattering images of the unburnt jet of fuel/air. Combustion noise which corresponds to the stable operation of the combustor is associated with the incoherent fluctuations in the flow and aperiodic irregular oscillations in unsteady pressure. In contrast, full blown thermoacoustic instability is associated with self-organized coherent vortex structures in the flow and ordered regular fluctuations in the acoustic pressure. Between irregularity (combustion noise) and order (thermoacoustic instability), the intermediate state 'intermittency' have characteristics of both combustion noise and thermoacoustic instability. Intermittency is manifested as seemingly random appearance of bursts of high-amplitude periodic oscillations amidst regions of low-amplitude aperiodic fluctuations in the acoustic pressure. During intermittency, in the low-amplitude regime, we observe incoherent, seemingly random, fluctuations in the flow. However, in the high-amplitude regime during intermittency, we observe coherent vortices in the flow. As we change the control parameter towards the condition of thermoacoustic instability, self-organized coherent vortices exist longer in time. Finally self-sustained high-amplitude pressure oscillations and self-organized coherent vortex structures are observed at the occurrence of full-blown thermoacoustic instability.
机译：当燃烧器内部的燃烧器的位置改变时，通过间歇地从燃烧噪声从燃烧噪声从燃烧噪声转变为热声噪声。通过同时测量声压，CH〜*化学发光图像的火焰和燃料射流的火焰和MIE散射图像的同时测量，捕获火焰，流动和管道声学的耦合导致从燃烧噪声转换到热声不稳定性的作用。空气。其对应于所述燃烧器的稳定操作与在流动的非相干的波动和非周期性不规则振荡不稳定压力相关联的燃烧噪声。相比之下，完全吹动的热声不稳定性与流动中的自组织相干涡流结构相关联，并在声压中有序常规波动。在不规则（燃烧噪声）和顺序（热声不稳定性）之间，中间状态“间间”具有燃烧噪声和热声不稳定性的特征。间歇性表现为看似随机外观的高幅度周期振荡突发，在声压低的低幅度非周期性波动区域中。在间歇性期间，在低幅度制度中，我们观察到流动中的不连贯，看似随机的波动。然而，在间歇性期间的高幅度制度中，我们观察流程中的相干涡流。当我们改变控制参数朝向热声不稳定性的条件时，自组织的相干涡流随时间更长。最后在出现全吹热的无稳定性时观察到自持续的高幅度压力振荡和自组织的相干涡流结构。

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