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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/341508721 Experimental investigation of vortex ring interaction with a permeable flat surface Presentation Presentation May 2006

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See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/341508721

Experimental investigation of vortex ring interaction with a permeable flat surface – Presentation

Presentation · May 2006

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3 authors, including: Some of the authors of this publication are also working on these related projects: Natural Convection Inside Porous Media View project Analysis of gas transport and micro-circulation in pulmonary capillaries View project

  • C. Naaktgeboren

Federal University of Technology - Paraná/Brazil (UTFPR)

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Paul S Krueger Southern Methodist University

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Experimental Investigation of Vortex Ring Interaction with a Permeable Flat Surface Experimental Investigation of Vortex Ring Interaction with a Permeable Flat Surface

Christian Naaktgeboren Paul S. Krueger José L. Lage

Department of Mechanical Engineering Southern Methodist University Dallas, Texas 3rd International Conference on Applications of Porous Media – 3ICAPM Monday–Saturday, May 29–June 3, 2006; Marrakech, MOROCCO

Work partially supported by NSF grant CTS–0347958

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Background: Vortex Ring Generation Background: Vortex Ring Generation

Parameters: a) Time history of piston velocity (velocity program) b) L/D c) Reynolds Number d) Orifice/nozzle Geometry

Classical Piston-Cylinder Mechanism:

t

tp Up(t) Starting Jet

  • r

“Pulse” L D

uJ(r, t)

[Didden, 1977]

U0

ν D U Re =

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Motivation for Present Investigation Motivation for Present Investigation

  • Interaction of a compact vortical structure with

a complex interface

– Vorticity generation – Effect on convection and vorticity transport – Kinetic energy dissipation

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Examples Examples

  • Nature

– Jellyfish with tentacles – Microbursts – Vortex-structure interaction

  • Engineering

– Chemical reactions near/within PM – Filter cleaning – Electronics cooling – Sampling of contaminants

  • n clothing
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Previous Work – Vortex Ring Impingement Previous Work – Vortex Ring Impingement

  • Collision of two coaxial vortex rings

– Helmholtz, H., 1867; – Dyson, F. W., 1893; – Lim, T. T., Nickels T. B., and Chong, M.S., 1991.

  • Flat, rigid, impermeable surface

– Magarvey, R. H., and MacLatchy C. S., 1963; – Cerra, A. W., Smith, C. R., 1983. – Verzicco, R., and Orlandi, P., 1994.

  • Actively controlled mass flux through wall

– Koumoutsakos, P., 1997.

  • Thin porous screen (flow visualization)

– Naaktgeboren C. et al, 2005.

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Experimental Configuration Experimental Configuration

TARGET CCD CAMERA RING VORTEX ARGON ION LASER Nd:YAG LASER PISTON-CYLINDER MECHANISM

L D

VESSEL PRESSURE AIR WATER GENERATOR PULSE/DELAY NC PLANAR LIGHT SHEET

  • Measurement techniques

– Planar Laser Induced Fluorescence (PLIF) – Digital Particle Image Velocimetry (DPIV)

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PLIF & DPIV Raw Data PLIF & DPIV Raw Data

PLIF DPIV

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DPIV – Processed Results DPIV – Processed Results

Velocity Field Vorticity

u ω × ∇ =

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Porous Targets Porous Targets

Target #2:

1.57 Pore aspect ratio: 29.4 D/Dpore: (267±13) µm Thickness (e): (58±4) % Surface fraction (φ):

Target #3:

1.02 Pore aspect ratio: 8.75 D/Dpore : (594±5) µm Thickness (e): (86.6±0.3) % Surface fraction (φ):

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SLIDE 11

Flow evolution – φ=0, Re=3000, L/D=1.00 Flow evolution – φ=0, Re=3000, L/D=1.00

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Vorticity (ωθ) – φ=0 Vorticity (ωθ) – φ=0

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Kinetic Energy Distribution – φ=0 Kinetic Energy Distribution – φ=0

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Flow evolution – φ=0.58, Re=3000, L/D=1.00 Flow evolution – φ=0.58, Re=3000, L/D=1.00

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Vorticity (ωθ) – φ=0.58 Vorticity (ωθ) – φ=0.58

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Vorticity – φ=0.58, Re=3000, L/D=1.00 Vorticity – φ=0.58, Re=3000, L/D=1.00

Levels every 2.5 s−1 Levels every 1.0 s−1

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Kinetic Energy Distribution – φ=0.58 Kinetic Energy Distribution – φ=0.58

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Flow evolution – φ=0.866, Re=3000, L/D=1.00, ψ Flow evolution – φ=0.866, Re=3000, L/D=1.00, ψ

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Vorticity (ωθ) – φ=0.866 Vorticity (ωθ) – φ=0.866

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Vorticity – φ=0.866, Re=3000, L/D=1.00 Vorticity – φ=0.866, Re=3000, L/D=1.00

Levels every 2.5 s−1 Levels every 1.0 s−1

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Kinetic Energy Distribution – φ=0.866 Kinetic Energy Distribution – φ=0.866

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Total Kinetic Energy History Total Kinetic Energy History

φ=58.0% φ=86.6%

∫∫

= dz dr r T

2

u π ρ

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Kinetic Energy Relations Kinetic Energy Relations

53.9±0.6 46.1±0.6 negligible 108.4±0.6 0.866 94.8±0.6 2.48±0.25 2.66±0.38 107±2

0.58

−∆T/T (%) TVRT/TVR1 (%) TVR2/TVR1 (%) VR1: T/ρ (mm5/s2) φ

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Conclusions Conclusions

  • High porosity targets

– No vortex rebound

  • Separated features

convected downstream

– Significant through- flow – Moderate viscous dissipation – Spreading of the vortex core

  • Low porosity targets

– Vortex rebound

  • Flow separation
  • Secondary vortices

– Reduced through-flow – Intense viscous dissipation – Reorganization of the transmitted ring

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