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首页> 外文会议>AIAA/ASME/SAE/ASEE joint propulsion conference exhibit >Influence of flow-structure dynamics on thermo-acoustic instabilities in oscillating swirl flames
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Influence of flow-structure dynamics on thermo-acoustic instabilities in oscillating swirl flames

机译：流结构动力学对振荡涡流火焰中热声不稳定性的影响

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The thermo-acoustic coupling caused by dynamic flow-flame interactions was investigated in a gas turbine model combustor through analysis of high-repetition-rate laser measurements. Planar three-component velocity fields and OH radical distributions, as well as the line-of-sight integrated chemiluminescence from OH*, were measured at a sustained repetition rate of 5 kHz. Three fuel-lean, swirl-stabilized flames were investigated, each of which underwent thermo-acoustic pulsations. The most energetic flow structure at each condition was a helical vortex core that spiraled around the burner axis and circumscribed the combustor at a rate that was independent of the acoustics. By resolving the measurement sequence with respect to both the phase in the thermo-acoustic cycle and the azimuthal position of the helical vortex core, the repeatable oscillatory processes could be reconstructed in three dimensions. Periodic deformations in the helices at the thermo-acoustic frequency were found to cause oscillations in the flame surface area. The local flame area oscillated either in- or out-of-phase with the acoustic pulsations depending on the relative shapes of the flame and helices. To investigate this further, the local thermo-acoustic coupling was determined by statistically solving the Rayleigh integral. In all cases, intertwined regions of positive and negative coupling occurred near the burner nozzle due to the helical vortices. In the quietest flame, the helical vortex created a large region of negative coupling that helped damp the thermo-acoustic oscillations. In the moderately louder flame, the shapes of the helix and flame were such that there was a large helical region of positive thermo-acoustic coupling that contributed energy to the thermo-acoustic pulsations. In the loudest flame, positive thermo-acoustic coupling occurred in both a large helical region and in the outer recirculation zone.
机译：通过分析高重复频率激光测量，在燃气轮机模型燃烧器中研究了由动态流-火焰相互作用引起的热声耦合。以5 kHz的持续重复频率测量了平面三分量速度场和OH自由基分布以及OH *的视线积分化学发光。研究了三种贫油，旋流稳定的火焰，每个火焰都经历了热声脉动。在每种情况下，最有活力的流动结构是螺旋形涡流芯，螺旋形涡流芯围绕燃烧器轴线盘旋，并以与声学无关的速率围绕燃烧器。通过解析关于热声循环中的相位和螺旋涡流芯的方位角位置的测量序列，可以在三个维度上重构可重复的振荡过程。发现在热声频率下螺旋的周期性变形会引起火焰表面积的振荡。取决于火焰和螺旋的相对形状，局部火焰区域与声脉冲同相或异相振动。为了进一步研究，通过统计求解瑞利积分来确定局部热声耦合。在所有情况下，由于螺旋涡流，在燃烧器喷嘴附近都会发生正负耦合的交织区域。在最安静的火焰中，螺旋涡旋形成了很大的负耦合区域，有助于抑制热声振荡。在中等响亮的火焰中，螺旋和火焰的形状使得存在一个大的正热声耦合螺旋区域，从而为热声脉动贡献能量。在最响的火焰中，大的螺旋区域和外部再循环区域都发生了正的热声耦合。

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