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Experimental investigation of three-dimensional vortex structures downstream of vortex generators over a backward-facing step

Ma, Xingyu and Geisler, Reinhard and Schröder, Andreas (2017) Experimental investigation of three-dimensional vortex structures downstream of vortex generators over a backward-facing step. Flow Turbulence and Combustion, 98 (2), pp. 389-415. Springer. DOI: 10.1007/s10494-016-9768-8 ISSN 1386-6184

Full text not available from this repository.

Official URL: https://link.springer.com/content/pdf/10.1007/s10494-016-9768-8.pdf

Abstract

An experimental investigation of vortex generators has been carried out in turbulent backwardfacing step (BFS) flow. The Reynolds number, based on a freestream velocity U_0 = 10 m/s and a step height h = 30 mm, was Re_h = 2.0×10^4. Low-profile wedgetype vortex generators (VGs) were implemented on the horizontal surface upstream of the step. Highresolution planar particle image velocimetry (2D-2C PIV) was used to measure the separated shear layer, recirculation region and reattachment area downstream of the BFS in a single field of view. Besides, timeresolved tomographic particle image velocimetry (TR-Tomo-PIV) was also employed to measure the flow flied of the turbulent shear layer downstream of the BFS within a three-dimensional volume of 50×50×10 mm^3 at a sampling frequency of 1 kHz. The flow control result shows that time-averaged reattachment length downstream of the BFS is reduced by 29.1% due to the application of the VGs. Meanwhile, the Reynolds shear stress downstream of the VGs is considerably increased. Proper Orthogonal Decomposition (POD) and Dynamic Mode Decomposition (DMD) have been applied to the 3D velocity vector fields to analyze the complex vortex structures in the spatial and temporal approaches, respectively. A coherent bandwidth of Strouhal number 0.3 < St_h < 0.6 is found in the VG-induced vortices, and moreover, Λshaped threedimensional vortex structures at St_h = 0.37 are revealed in the energy and dynamic approaches complementarily.

Item URL in elib:https://elib.dlr.de/105910/
Document Type:Article
Title:Experimental investigation of three-dimensional vortex structures downstream of vortex generators over a backward-facing step
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Ma, XingyuXingyu.Ma (at) dlr.deUNSPECIFIED
Geisler, Reinhardreinhard.geisler (at) dlr.deUNSPECIFIED
Schröder, AndreasAndreas.Schroeder (at) dlr.deUNSPECIFIED
Date:2017
Journal or Publication Title:Flow Turbulence and Combustion
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:98
DOI :10.1007/s10494-016-9768-8
Page Range:pp. 389-415
Publisher:Springer
ISSN:1386-6184
Status:Published
Keywords:Coherent structure · Vortex generator · Backward-facing step · Particle Image velocimetry · Proper Orthogonal Decomposition · Dynamic Mode Decomposition
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
Institutes and Institutions:Institute for Aerodynamics and Flow Technology > Experimental Methods, GO
Deposited By: Bachmann, Barbara
Deposited On:16 Dec 2016 12:07
Last Modified:06 Sep 2019 15:21

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