Influence of Air and Fuel Mass Flow Fluctuations in a Premix Swirl Burner on Flame Dynamics
Influence of Air and Fuel Mass Flow Fluctuations in a Premix Swirl Burner on Flame Dynamics
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预混旋流燃烧器中空气和燃料质量流量波动对火焰动力学的影响
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
T. Sattelmayer
中科院分区：
文献类型：
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作者：
M. Auer;C. Hirsch;T. Sattelmayer
本文讨论了振荡预混湍流旋流火焰中观察到的结构变化，并在天然气旋流燃烧器预热大气试验台上演示了调制质量流对火焰动力学的影响。实验研究了旋流稳定预混火焰的自激和强迫燃烧振荡，发现在声学驱动的质量流振荡和火焰的积分放热率之间存在不同的时间延迟。高速的OH~-化学发光薄膜揭示了火焰结构随振荡频率和燃料质量流振荡与燃烧器出口总质量流之间的相位角的变化情况。发现这些参数决定了热释放的时空分布，从而决定了净释放热的波动。因此，即使在声学致密火焰的情况下，沿火焰长度的时空热释放分布也对热声耦合有影响。用一维解析模型进一步讨论了观测到的现象。它强调，对于旋流稳定的预混湍流火焰，流场扰动的动力学在产生有效热释放波动中起着主要作用。版权所有©2006，ASME
This paper discusses the structural changes observed in oscillating premixed turbulent swirling flames and demonstrates the influence of modulated mass flows on the flame dynamics in a preheated atmospheric test rig with a natural gas fired swirl burner. The experimentally investigated self excited and forced combustion oscillations of swirl stabilized premixed flames show varying time delays between the acoustically driven mass flow oscillations and the integral heat release rate of the flame. High speed films of the OH*-chemiluminescence reveal how the flame structure changes with the oscillation frequency and the phase angle between the fuel mass flow oscillation and the total mass flow at the burner exit. These parameters are found determine the spatial and temporal heat release distribution and thus the net heat release fluctuation. Therefore, the spatial and temporal heat release distribution along the flame length has an influence on the thermoacoustic coupling, even in the case of acoustically compact flames. The observed phenomena are discussed further using an 1-d analytical model. It underscores that for swirl stabilized premixed turbulent flames the dynamics of the flow field perturbation play a major role in creating the effective heat release fluctuation.Copyright © 2006 by ASME