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Near-wall turbulence characterization using 4D-PTV “Shake-The-Box”

Schröder, Andreas and Schanz, Daniel and Geisler, Reinhard and Novara, Matteo and Willert, Christian (2015) Near-wall turbulence characterization using 4D-PTV “Shake-The-Box”. 11th International Symposium on Particle Image Velocimetry - PIV2015, 14. - 16. Sept. 2015, Santa Barbara, CA, USA.

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Official URL: http://www.piv2015.org

Abstract

A near-wall flow characterization including measurements of instantaneous wall-shear stresses of a turbulent boundary layer (TBL) developing along a flat plate with zero pressure gradients has been performed by using two advanced particle based measurement methods. The experiments were conducted in the 1m- wind tunnel facility of Göttingen at U_∞ = 10 m/s and a Reynolds number of Re_θ = 2,770 corresponding to Re_τ = 960. First, high-speed 2C-PIV was performed at two image magnification factors at 2 kHz and 4 kHz frame rates in order to obtain the overall statistical properties of the boundary layer profile together with a large time series of instantaneous 2C velocity vector fields in a streamwise, wall-normal plane. Single pixel line correlation applied to the particle image area close to the wall provided high spatial resolution velocity data down into the viscous sublayer. In a second step, the novel 4D-PTV technique Shake-The-Box (STB) was applied to a time series of particle images acquired with a typical tomographic high-speed camera set-up at 15.873 kHz. The STB measurement domain consists of a wall-bounded volume covering a stream- and spanwise area of 430 x 430 viscous units (l^+= ν/u_τ) and a wall-normal extension of 32 viscous units. A comprehensive set of relatively dense Lagrangian track data was reconstructed from two time resolved sequences of 115,000 time steps each. The data enables an accurate and very high resolution measurement of the mean and rms-velocity profiles averaged in bins sized by a fraction of a viscous unit, of both components of the instantaneous wall shear stress (τ^+_w) and all components of the Reynolds stress tensor. Furthermore, the time-resolved 3D velocity vectors and corresponding gradient tensor have been interpolated onto a regular grid using the time series of irregularly distributed Lagrangian track data. With the present data coherent structures and their dynamics close to the wall can be investigated together with their role for various (rare) wall shear stress events. The STB method is proven capable of coping with strong velocity gradients close to walls and can also be extended to TBL flows with much higher Reynolds numbers.

Item URL in elib:https://elib.dlr.de/95223/
Document Type:Conference or Workshop Item (Speech)
Title:Near-wall turbulence characterization using 4D-PTV “Shake-The-Box”
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Schröder, Andreasandreas.schroeder (at) dlr.deUNSPECIFIED
Schanz, Danieldaniel.schanz (at) dlr.deUNSPECIFIED
Geisler, Reinhardreinhard.geisler (at) dlr.deUNSPECIFIED
Novara, Matteomatteo.novara (at) dlr.deUNSPECIFIED
Willert, Christianchris.willert (at) dlr.deUNSPECIFIED
Date:2015
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Page Range:pp. 1-14
Series Name:Conference Proceedings on USB-stick
Status:Published
Keywords:turbulent boundary layer, friction velocity, Shake-The-Box, high-speed PIV
Event Title:11th International Symposium on Particle Image Velocimetry - PIV2015
Event Location:Santa Barbara, CA, USA
Event Type:international Conference
Event Dates:14. - 16. Sept. 2015
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Simulation and Validation
Location: Göttingen , Köln-Porz
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Institute of Propulsion Technology > Engine Measurement Systems
Deposited By: Micknaus, Ilka
Deposited On:29 Sep 2015 14:44
Last Modified:31 Jul 2019 19:51

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