Study of Dynamical Instabilities in Siemens Liquid Spray Injectors Using Complementary Modal Decomposition Techniques
Study of Dynamical Instabilities in Siemens Liquid Spray Injectors Using Complementary Modal Decomposition Techniques
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DOI：
10.1115/gt2019-91473
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
Adesile Ajisafe;M. Talibi;A. Ducci;R. Balachandran;N. Parsania;S. Sadasivuni;G. Bulat
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文献类型：
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作者：
Adesile Ajisafe;M. Talibi;A. Ducci;R. Balachandran;N. Parsania;S. Sadasivuni;G. Bulat
液体燃料喷雾特性对于理解燃料能量释放和污染物形成的机制至关重要。操作条件的仔细选择可以促进燃料喷雾中的流动不稳定性，这可以增强雾化和燃料混合，从而导致更有效的燃烧。然而，喷雾中存在的固有不稳定性可能对燃烧室动力学产生不利影响。因此，更好地理解喷雾的动态行为，特别是在代表性的操作条件下，是很重要的。本文介绍了在一系列燃烧室压力和喷油压力下，利用高速激光平面成像技术对西门子工业燃气涡轮机燃烧室中使用的压力旋流雾化器的动态特性进行的实验研究。两个模态分解技术-本征正交分解（POD）和动态模态分解（DMD）-应用和比较，以评估喷雾动力学。结果表明，POD和DMD都能够捕捉到周期性结构发生在喷雾在不同的空间长度尺度。两种方法估计的特征频率吻合较好。这两种技术都能够识别具有可变尺寸、形状和交错水平的相干结构，观察到这取决于雾化器和腔室压力之间的压差。时空分辨的数据和结果可用于喷雾模型的开发和验证。此外，所采用的方法可以应用于其他燃料雾化器，以及涉及交叉流和较高室温度的更复杂的条件。
Liquid fuel spray characterisation is essential for understanding the mechanisms underlying fuel energy release and pollutant formation. Careful selection of operating conditions can promote flow instabilities in the fuel spray which can enhance atomisation and fuel mixing, thereby resulting in more efficient combustion. However, the inherent instabilities present in the spray could have adverse effect on the combustor dynamics. Hence, it is important to better understand the dynamical behaviour of the spray, and particularly at representative operating conditions. This work describes an experimental investigation of dynamical behaviour of pressure-swirl atomisers used in Siemens industrial gas turbine combustors, at a range of chamber pressures and fuel injection pressures, using high speed laser planar imaging. Two modal decomposition techniques — Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) — are applied and compared to assess the spray dynamics. Results indicate that both POD and DMD are able to capture periodic structures occurring in the spray at different spatial length scales. The characteristic frequencies estimated from both the methods are in good agreement with each other. Both techniques are able to identify coherent structures with variable size, shape and level of staggering, which are observed to be dependent on the pressure difference across the atomiser and the chamber pressure. The spatio-temporally resolved data and the results could be used for spray model development and validation. Furthermore, the methods employed could be applied to other fuel atomisers, and more complicated conditions involving cross flow and higher chamber temperatures.