Phase-Averaging Methods for a Naturally Oscillating Flow Field
Phase-Averaging Methods for a Naturally Oscillating Flow Field
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自然振荡流场的相位平均方法
DOI：
10.2514/6.2014-1142
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发表时间：
2014
影响因子：
1.8
通讯作者：
C. Paschereit
中科院分区：
文献类型：
--
作者：
Florian Ostermann;R. Woszidlo;S. Gaertlein;C. Nayeri;C. Paschereit
本研究探讨了各种方法的相位平均的自然振荡流场的放大流体振荡器获得的高速PIV系统。由于没有外部触发，对采集的数据进行相位平均是一项挑战。数学和物理方法进行了分类和描述。这些方法的结果进行评估，其准确性在捕捉自然流场。结果表明，数学方法，特别是本征正交分解法，能给出合理的定性结果。然而，与物理方法相比，在定量准确性方面存在不足。物理方法需要时间分辨的参考信号。两种可能性，以确定在参考信号中的振荡周期的描述和比较。据发现，应用自相关的参考信号，提高了由于考虑到局部波动的平均值的周期识别。该周期识别方法和相应的相位平均产生关于振荡周期长度的最小波动的最佳结果。详细介绍了相应的计算方法，并将其应用于射流振荡器的内外流场。
The presented study examines various methods for phase-averaging the naturally oscillating flow field of an enlarged fluidic oscillator acquired by a high-speed PIV system. Because of the absence of an external trigger, phase-averaging the acquired data is challenging. Mathematical and physical methods are categorized and described. The results of these methods are evaluated for their accuracy in capturing the natural flow field. It is found that the mathematical methods, especially the method of proper orthogonal decomposition, produce reasonable qualitative results. However, compared to the physical methods, shortcomings in quantitative accuracy are revealed. The physical methods require a time-resolved reference signal. Two possibilities to identify the oscillation periods in the reference signal are described and compared. It is found that applying an autocorrelation on the reference signal improves the period identification due to consideration of a locally fluctuating mean value. This period identification method and according phase-averaging yields the best results regarding the minimum fluctuation of the oscillation period lengths. The according procedure is described in detail and applied to the internal and external flow field of the fluidic oscillator.