On the Impact of Shear Flow Instabilities on Global Heat Release Rate Fluctuations: Linear Stability Analysis of an Isothermal and a Reacting Swirling Jet
On the Impact of Shear Flow Instabilities on Global Heat Release Rate Fluctuations: Linear Stability Analysis of an Isothermal and a Reacting Swirling Jet
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剪切流不稳定性对整体放热率波动的影响：等温和反应旋流射流的线性稳定性分析
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发表时间：
2012
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通讯作者：
C. Paschereit
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作者：
K. Oberleithner;S. Schimek;C. Paschereit
预测燃烧室流动中的大尺度流动结构及其对火焰动力学的影响，对于现代燃气涡轮机设计中避免热声不稳定性具有重要意义。这些所谓的相干结构的流向增长取决于剪切层的感受性，这可以通过线性稳定性分析数值预测。我们证明了这种方法上的等温旋转射流是由一个自激螺旋模式，具有旋进涡核占主导地位，表明这种理论概念成功地预测的频率，源，和这种模式的形状。分析进一步施加到一个反应流与旋流稳定的火焰，指出剪切层的感受性和测量的火焰传递函数的振幅依赖性之间的重要连接。理论研究结果表明，在中等强迫振幅下观测到的全球热释放率波动的饱和是由剪切层感受性消失引起的。
The prediction of large-scale flow structures in combustor flows and their impact on the flame dynamics is of great importance to avoid thermoacoustic instabilities in modern gas turbine design. The streamwise growth of these so-called coherent structures depends on the receptivity of the shear layers, which can be predicted numerically by means of linear stability analysis. We demonstrate this approach on an isothermal swirling jet that is dominated by a self-excited helical mode that features a precessing vortex core, showing that this theoretical concept successfully predicts the frequency, the source, and the shape of this mode. The analysis is further applied to a reacting flow with a swirl-stabilized flame, pointing out important connections between the shear layer receptivity and the measured amplitude dependence of the flame transfer function. The theoretical findings suggest that the saturation of the global heat release rate fluctuations observed at moderate forcing amplitudes is caused by vanishing shear layer receptivity.Copyright © 2012 by ASME