An analytical model for the impulse response of laminar premixed flames to equivalence ratio perturbations
An analytical model for the impulse response of laminar premixed flames to equivalence ratio perturbations
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DOI：
10.1016/j.proci.2016.06.002
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Alp Albayrak;Ralf S. Blumenthal;A. Ulhaq;W. Polifke
中科院分区：
文献类型：
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作者：
Alp Albayrak;Ralf S. Blumenthal;A. Ulhaq;W. Polifke
利用水平集方法(“G方程”)，在时间域内分析了锥形层流预混火焰对当量比波动的动态响应。在火焰底部施加的当量比扰动向火焰前沿对流，在那里它们引起火焰速度、反应热和火焰形状的调制。由此产生的放热率波动以各自的脉冲响应函数的闭合形式表示。确定了与这些机制相对应的时间尺度，讨论了它们对整体火焰冲量响应的贡献。如果脉冲响应函数被拉普拉斯变换到频域，则观察到与先前关于火焰频率响应的结果一致。提出了考虑分子扩散引起的当量比波动弥散的模型的扩展。色散模型揭示了预混火焰动力学对火焰与喷油器之间距离的敏感性。将模型计算结果与层流预混火焰的数值模拟结果进行了比较。
The dynamic response of conical laminar premixed flames to fluctuations of equivalence ratio is analyzed in the time domain, making use of a level set method (“G-Equation”). Perturbations of equivalence ratio imposed at the flame base are convected towards the flame front, where they cause modulations of flame speed, heat of reaction and flame shape. The resulting fluctuations of heat release rate are represented in closed form in terms of respective impulse response functions. The time scales corresponding to these mechanisms are identified, their contributions to the overall flame impulse response are discussed. If the impulse response functions are Laplace transformed to the frequency domain, agreement with previous results for the flame frequency response is observed. An extension of the model that accounts for dispersion of equivalence ratio fluctuations due to molecular diffusion is proposed. The dispersive model reveals the sensitivity of the premixed flame dynamics to the distance between the flame and the fuel injector. The model results are compared against numerical simulation of a laminar premixed flame.