Experiments on very large structures in fully developed turbulent pipe flow

充分发展的湍流管流中超大型结构的实验

• 批准号: 315905061
• 负责人: Professor Dr.-Ing. Christoph Egbers
• 金额: --
• 依托单位: Lehrstuhl Aerodynamik und Strömungslehre
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/315905061?language=en
• 关键词: Experiments; very; large; structures; fully

The present work aims at investigation of turbulent pipe flow at high Reynolds numbers and low Mach numbers. During the recent years there has been an increasing interest in observation and understanding of large scale turbulent coherent structures, which are commonly known as Large and Very Large Scale Motions (LSM and VLSM). Nevertheless, a solid definition of their nature and vivid understanding of their evolution is still incomplete. Therefore, this study will focus on clarifying the nature and origin of LSM and VLSM as well as describing and identifying them in a quantitative manner. To this end, experiments and numerical computations (together with possible partners within the SPP) will be performed and matched as closely as possible. Experiments at Cottbus Large Pipe Test Facility (CoLa-Pipe), which was used successfully along the first phase, will be conducted at bulk Reynolds numbers of 6x10E4 ≤ Re b ≤ 1x10E6 (based on pipe diameter D and bulk velocity Ub) and Mach numbers Ma < 0.23, measuring turbulent flow properties using miniaturized Hot Wire Anemometry (HWA), high speed Particle Image Velocimetry (PIV) and Shake The Box (STB) particle tracking technique (in collaboration with DLR, A. Schröder).This proposal aims at two prominent objectives. Both objectives build on our findings in the first phase of this study and they will expand our understanding of turbulent structures using the measurement techniques which provide higher spatial and temporal resolutions. Our first goal is to clarify the uncertainties concerning scaling of structural turbulence properties using miniaturized HWA and 3D high resolution profile measurements. The second goal is to quantify the kinematics and dynamics of large-scale coherent structures. The length scales, energy contents and wall-normal locations of such structures have been already determined in pre-multiplied energy spectra during the first phase of this study. In the second phase, we will extract low order subspaces of highly dimensional turbulent flow, from 2D and 3D time-resolved measurements on a moving frame of reference by applying a Characteristic DMD (in collaboration with TU Berlin, J. Sesterhenn). Optimized combinations of extracted subspaces with long life times will form reduced order models, which accommodate structures that are known to be responsible for the formation of the spectral peaks. Life times and spatio-temporal evolutions of each group of structures will be studied in absence of small-scale structures. This will allow to determine how such structures contribute to turbulence properties such as TKE budgets, Reynolds stress and viscous shear stress.

目前的工作旨在以高雷诺数数量和低马赫数的投资投资。近年来，人们对大规模湍流相干结构的观察和理解越来越兴趣，这些结构通常称为大型且非常大的运动（LSM和VLSM）。然而，对其性质的扎实定义和对进化的生动理解仍然不完整。因此，这项研究将着重于阐明LSM和VLSM的性质和起源，并以定量的方式描述和识别它们。为此，将执行并尽可能近地进行实验和数值计算（以及SPP中可能的伙伴）。在第一阶段成功使用了Cottbus大型管道测试设施（COLA-PIPE）的实验，将以6x10e4≤REB≤1x10E6的大量雷诺数进行（基于管道直径D和Bulk d和bulk速度Ub）和Mach数字MA <0.23，使用MACH NOMBE MA <0.23，使用MACH NOME MA <0.23，使用驱动式流量质量速度（用于驱动式流动式）。 Velocimetry（PIV）并摇动盒子（STB）粒子跟踪技术（与DLR，A.Schröder合作）。此提案针对两个突出的目标。这两个目标都基于我们在本研究的第一阶段的发现，它们将使用提供更高空间和临时分辨率的测量技术来扩展我们对湍流结构的理解。我们的第一个目标是阐明使用微型HWA和3D高分辨率剖面测量值的结构湍流特性缩放的不确定性。第二个目标是量化大规模相干结构的运动学和动力学。在本研究的第一阶段，已经确定了此类结构的长度尺度，能量内容和壁正常位置。在第二阶段，我们将通过应用特征DMD（与Tu Berlin，J。Sesterhenn合作）提取高度湍流的低阶子空间，这是从2D和3D时间分辨的参考框架上提取的。具有长寿命的提取子空间的优化组合将形成降低的订单模型，这些模型已知，这些结构被称为频谱峰的形成。在没有小规模结构的情况下，将研究每组结构的终身时间和时空演变。这将允许确定此类结构如何促进湍流特性，例如TKE预算，雷诺压力和粘性剪切应力。