Advanced Identification of Coherent Structures in Swirl-Stabilized Combustors
Advanced Identification of Coherent Structures in Swirl-Stabilized Combustors
复制标题
涡流稳定燃烧器中相干结构的高级识别
DOI：
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发表时间：
2016
期刊：
影响因子：
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通讯作者：
K. Oberleithner
中科院分区：
文献类型：
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作者：
M. Sieber;C. Paschereit;K. Oberleithner
本文介绍了一种新引入的方法，用于分析旋涡稳定燃烧室流场的时间分辨实验数据。该方法是在经典的固有正交分解（POD）的基础上，通过时间约束进行扩展。该方法中嵌入的滤波操作允许从经典POD到傅里叶模式分解的连续衰落。这种新方法被称为光谱固有正交分解（SPOD），由于对现象进行了清晰的光谱分离，可以更清楚地分离出主要机制。本文简要介绍了SPOD的基本原理。实际的重点放在燃烧室流的应用程序上。本文分析了不同工况下燃烧室流场的高速PIV测量结果。在这些测量中，我们考虑了外部驱动和自然动力学，并揭示了自然模式和驱动模式如何相互作用。如本文所示，SPOD提供了旋涡火焰中相干结构的详细信息。发现两种不同的PVC结构受到声驱动的影响非常不同。相干结构与热释放波动有关，热释放波动来源于同时获得的OH*化学发光测量。除驱动模态外，低频模态对全球热释放波动有显著影响。*寄给作者的所有信件：moritz.sieber@tu-berlin.de名称a时间SPOD模式系数c相关系数g SPOD滤波器系数I OH*化学发光强度λ SPOD模式能量M空间点数N快照数N f SPOD滤波器大小Ω空间SPOD模式（化学发光）Φ空间SPOD模式（速度）q全局放热R相关矩阵S滤波后的相关矩阵St stroouhal数t时间v笛卡尔速度矢量[u，v，w] t x笛卡尔坐标矢量[x,y，z]引言从最新测量系统或计算流体动力学产生的大量数据中识别相关信息变得越来越困难。除了平均量之外，可用的时间分辨数据将重点放在流动中的动态现象上。感兴趣的动力学通常与大规模周期结构有关，也称为相干结构[1]。版权所有c©由ASME
We present an application of a newly introduced method to analyze the time-resolved experimental data from the flow field of a swirl-stabilized combustor. This method is based on classic proper orthogonal decomposition (POD) extended by a temporal constraint. The filter operation embedded in this method allows for continuous fading from the classic POD to the Fourier mode decomposition. This new method – called spectral proper orthogonal decomposition (SPOD) – allows for a clearer separation of the dominant mechanisms due to a clean spectral separation of phenomena. In this paper, the fundamentals of SPOD are shortly introduced. The actual focus is put on the application to a combustor flow. We analyze high-speed PIV measurements from flow fields in a combustor at different operation conditions. In these measurements, we consider externally actuated, as well as natural dynamics and reveal how the natural and actuated modes interact with each other. As shown in the paper, SPOD provides detailed insight into coherent structures in swirl flames. Two distinct PVC structures are found that are very differently affected by acoustic actuation. The coherent structures are related to heat release fluctuations, which are derived from simultaneously acquired OH* chemiluminescence measurements. Besides the actuated modes, a low frequency mode was found that significantly contribute to the global heat release fluctuations. ∗Address all correspondence to this author: moritz.sieber@tu-berlin.de NOMENCLATURE a Temporal SPOD mode coefficients c Correlation coefficient g SPOD filter coefficients I OH* chemiluminescence intensity λ SPOD mode energy M Number of spatial points N Number of snapshots N f Size of the SPOD filter Ω Spatial SPOD mode (chemiluminescence) Φ Spatial SPOD mode (velocity) q Global heat release R Correlation matrix S Filtered correlation matrix St Strouhal number t Time v Cartesian velocity vector [u,v,w]T x Cartesian coordinate vector [x,y,z]T INTRODUCTION It’s getting increasingly harder to identify the relevant information from the vast amount of data that is produced from recent measurement systems or computational fluid dynamics. Beside the mean quantities, the available time-resolved data put the focus towards dynamic phenomena in the flows. The dynamics of interest are usually related to large-scale periodic structures, also called coherent structures [1]. These are of major importance in 1 Copyright c © by ASME
影响因子：
1.9
作者：
S. Terhaar;T. Reichel;C. Schrödinger;Lothar Rukes;C. Paschereit;K. Oberleithner
通讯作者：
S. Terhaar;T. Reichel;C. Schrödinger;Lothar Rukes;C. Paschereit;K. Oberleithner