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Research Papers: Fundamental Issues and Canonical Flows

The Application of Different Tripping Techniques to Determine the Characteristics of the Turbulent Boundary Layer Over a Flat Plate

[+] Author and Article Information
Anton Silvestri

School of Mechanical Engineering,
University of Adelaide,
Adelaide, South Australia 5005, Australia
e-mail: anton.silvestri@adelaide.edu.au

Farzin Ghanadi

School of Mechanical Engineering,
University of Adelaide,
Adelaide, South Australia 5005, Australia
e-mail: farzin.ghanadi@adelaide.edu.au

Maziar Arjomandi

School of Mechanical Engineering,
University of Adelaide,
Adelaide, South Australia 5005, Australia
e-mail: maziar.arjomandi@adelaide.edu.au

Benjamin Cazzolato

School of Mechanical Engineering,
University of Adelaide,
Adelaide, South Australia 5005, Australia
e-mail: benjamin.cazzolato@adelaide.edu.au

Anthony Zander

School of Mechanical Engineering,
University of Adelaide,
Adelaide, South Australia 5005, Australia
e-mail: anthony.zander@adelaide.edu.au

Contributed by the Fluids Engineering Division of ASME for publication in the JOURNAL OF FLUIDS ENGINEERING. Manuscript received April 4, 2017; final manuscript received July 30, 2017; published online September 20, 2017. Assoc. Editor: Arindam Banerjee.

J. Fluids Eng 140(1), 011204 (Sep 20, 2017) (12 pages) Paper No: FE-17-1208; doi: 10.1115/1.4037675 History: Received April 04, 2017; Revised July 30, 2017

In the present study, the optimal two-dimensional (2D) tripping technique for inducing a naturally fully developed turbulent boundary layer in wind tunnels has been investigated. Various tripping techniques were tested, including wires of different diameters and changes in roughness. Experimental measurements were taken on a flat plate in a wind tunnel at a number of locations along the flat plate and at a variety of flow speeds using hot-wire anemometry to measure the boundary layer resulting from each tripping method. The results have demonstrated that to produce a natural turbulent boundary layer using a 2D protuberance, the height of the trip must be less than the undisturbed boundary layer thickness. Using such a trip was shown to reduce the development length of the turbulent boundary layer by approximately 50%. This was shown to hold true for all Reynolds numbers investigated (Rex=1.2×1051.5×106). The present study provides an insight into the effect of the investigated trip techniques on the induced transition of a laminar boundary layer into turbulence.

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Figures

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Fig. 1

Schematic of the experimental arrangement

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Fig. 2

(a) Error analysis of the turbulent velocity profile of the boundary layer at Reθ=1927: (o) experimental results, (..) results obtained by Marusic and Kunkel [27], and (--) results obtained by Schlatter and Orlu [28] and (b) error analysis of the laminar velocity profile of the boundary layer at Reθ=1927: (o) experimental data and (--) Blassius solution

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Fig. 3

(a) Mean velocity (U+) profile and (b) turbulence intensity (TU+) profile at  Rex=1.2×105, location 1: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, (Δ) rough sandpaper, (--) Marusic and Kunkel [27] data, and (-.-) Schlatter and Orlu [28] data

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Fig. 4

Mean velocity (U+) profile at location 2 for (a) Rex=5.3×105  and (b) Rex=7.5×105: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) Fine sandpaper, (◻) 5 mm step, (Δ) rough sandpaper, (--) Marusic and Kunkel [27] data, and (-.-) Schlatter and Orlu [28] data

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Fig. 5

Turbulence (TU+) intensity at location 2 for (a) Rex=5.3×105   and (b) Rex=7.5×105: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 6

(a) Mean velocity (TU+) profile and (b) turbulence intensity profile at  Rex=1.5×106, location 3: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, (Δ) rough sandpaper, (--) Marusic and Kunkel [27] data, and (-.-) Schlatter and Orlu [28] data

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Fig. 7

Shape factor, H, versus Reynolds number: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 8

Friction coefficient, Cf, versus Reynolds number based on momentum thickness. (x) Experimental data for the no trip data at all locations and (--) Sillero et al. [35] data.

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Fig. 9

VITA detection at location 3 at Y+ ≈ 15 for the 5 mm diameter rod trip, at Rex=1.0×106: (a) streamwise velocity fluctuations, (b) local variance, and (c) detector function

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Fig. 10

VITA detection at location 3 at Y+ ≈ 15 for the 5 mm diameter step trip, at Rex=1.0×106: (a) streamwise velocity fluctuations, (b) local variance, and (c) detector function

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Fig. 11

VITA events at location 3 at Y+ ≈ 15 for the 5 mm diameter rod trip, at Rex=1.5×106, for sweep events, where (--) is the ensemble average VITA sweep event

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Fig. 12

Average VITA sweep events at Rex=5.3×105, location 2: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 13

Average VITA sweep events at Rex=7.5×105, location 2: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 14

Average VITA sweep events at Rex=1.0×106, location 3: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 15

Average VITA sweep events at Rex=1.5×106, location 3: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 16

Average energy spectra at Rex=5.3×105: (a) y+ = 15, (b) y+ = 50, and (c) y+ = 150, location 2: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 17

Probability density function at Rex=1.5×106: (a) y+ = 50 and (b) y+ = 50, location 3: (o) no trip, (+) 5 mm trip, (x) 3 mm trip, (⋄) fine sandpaper, (◻) 5 mm step, and (Δ) rough sandpaper

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Fig. 18

Mean velocity profile for (a) Rex=2.2×105 and (b) Rex=3.1×105: (o) no trip, (x) 3 mm trip, (--) Marusic and Kunkel [27] data, and (-.-) Schlatter and Orlu [28] data

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Fig. 19

Turbulence intensity for (a) Rex=2.2×105 and (b) Rex=3.1×105: (o) no trip, (x) 3 mm trip, and (Δ) 3 mm trip at location 2

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