Multifractal Analysis of a Lobed Mixer Flowfield Utilizing the Proper Orthogonal Decomposition
Multifractal Analysis of a Lobed Mixer Flowfield Utilizing the Proper Orthogonal Decomposition
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DOI：
10.2514/3.11059
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发表时间：
1992-05
期刊：
影响因子：
2.5
通讯作者：
L. Ukeiley;M. Varghese;M. Glauser;D. Valentine
中科院分区：
文献类型：
--
作者：
L. Ukeiley;M. Varghese;M. Glauser;D. Valentine
本文利用多重分形测度理论对波瓣混合器流场的速度-时间曲线数据分析进行了新的探讨。波瓣混合器是一种通过二次流和流向涡量增强混合的装置。一个专门设计的高空间分辨率的热线耙用于收集流向速度数据。通过适当的正交分解，在能量加权的基础上，研究了相干结构的基本知识。计算广义分形维数所需的瞬时速度迹线是从适当的正交分解所采取的系综平均测量再现。本文计算了几个热线探针在不同能级上的速度-时间轨迹数据样本的广义分形维数Dq和几个本征模的/（α）多重分形谱。这是一个显着的偏离以前的多重分形理论的应用程序，主要是处理耗散领域的湍流动能的自相似叶栅。在本说明的过程中，将指出，在某些情况下，单个维度D1可能足以捕获速度时间轨迹的标度指数的整个频谱。我们验证，在这种情况下，热线探头的位置意味着缺乏的不稳定性。
We use the theory of multifractal measures to throw a fresh perspective on the data analysis of velocity time traces in a lobed mixer flow. A lobed mixer is a device that enhances mixing through secondary flows and streamwise vorticity. A specially designed rake of hot wires with high spatial resolution was used to collect the streamwise velocity data. Through the use of the proper orthogonal decomposition, a basic knowledge of the coherent structures, on an energy weighted basis, was studied. The instantaneous velocity traces that are necessary for calculating the generalized fractal dimensions are reproduced from the ensemble average measurements taken from the proper orthogonal decomposition. We compute the generalized fractal dimensions Dq and the /(a) multifractal spectrum of several proper eigenmodes for data samples from the velocity time trace of several hot-wire probes at different energy levels. This is a marked departure from previous multifractal theory applications to self-similar cascades that mainly dealt with the dissipation fields of turbulent kinetic energy. In the course of this exposition it will be pointed out that in certain cases a single dimension D\ may suffice to capture the entire spectrum of scaling exponents for the velocity time trace. We verify that in such cases the location of the hot-wire probes imply a lack of intermittency .