0
TECHNICAL PAPERS

Turbulent Transport in Pin Fin Arrays: Experimental Data and Predictions

[+] Author and Article Information
F. E. Ames

Mechanical Engineering Department,  University of North Dakota, Grand Forks, ND 98202forest_ames@mail.und.nodak.edu

L. A. Dvorak

 Sandia National Laboratories, P.O. Box 5800, MS 776, Albuquerque, NM 87185

J. Turbomach 128(1), 71-81 (Feb 01, 2005) (11 pages) doi:10.1115/1.2098792 History: Received October 01, 2004; Revised February 01, 2005

The objective of this research has been to experimentally investigate the fluid dynamics of pin fin arrays in order to clarify the physics of heat transfer enhancement and uncover problems in conventional turbulence models. The fluid dynamics of a staggered pin fin array has been studied using hot wire anemometry with both single- and x-wire probes at array Reynolds numbers of 3000, 10,000, and 30,000. Velocity distributions off the endwall and pin surface have been acquired and analyzed to investigate turbulent transport in pin fin arrays. Well resolved 3D calculations have been performed using a commercial code with conventional two-equation turbulence models. Predictive comparisons have been made with fluid dynamic data. In early rows where turbulence is low, the strength of shedding increases dramatically with increasing Reynolds numbers. The laminar velocity profiles off the surface of pins show evidence of unsteady separation in early rows. In row three and beyond, laminar boundary layers off pins are quite similar. Velocity profiles off endwalls are strongly affected by the proximity of pins and turbulent transport. At the low Reynolds numbers, the turbulent transport and acceleration keep boundary layers thin. Endwall boundary layers at higher Reynolds numbers exhibit very high levels of skin friction enhancement. Well-resolved 3D steady calculations were made with several two-equation turbulence models and compared with experimental fluid mechanic and heat transfer data. The quality of the predictive comparison was substantially affected by the turbulence model and near-wall methodology.

Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Internal heat transfer and flow facility showing staggered pin fin array test section

Grahic Jump Location
Figure 2

Near-pin velocity and u′ distributions off row 1 pin at 90deg, normalized by Vmax

Grahic Jump Location
Figure 3

Time-dependent near-pin velocity off row 1 pin, ReDmax=30,000, Vmax=18.98m∕s

Grahic Jump Location
Figure 4

Near-pin velocity normalized on Vmax versus time normalized on D∕Vmax, pin 1, 90deg, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 5

One-dimensional power spectra of u′ off row 1 pin showing peak shedding wave number, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 6

Row 1 midline Nu∕ReDeff1∕2 as a function of angle, showing the effect of shedding on pin backside heat transfer compared to realizable k-ε, ReDmax=3000, 10,000, and 30,000

Grahic Jump Location
Figure 7

Near-pin velocity and u′ distributions off row 2 pin at 90deg, normalized by Vmax

Grahic Jump Location
Figure 8

Near-pin velocity normalized on Vmax versus time normalized on D∕Vmax, row 2, 90deg, ReDmax=3000, 10,000, and 30,000

Grahic Jump Location
Figure 9

Row 2 midline Nu∕ReDeff1∕2 as a function of angle, showing the effect of shedding on pin backside heat transfer compared to realizable k-ε, ReDmax=3000, 10,000, and 30,000

Grahic Jump Location
Figure 10

Near-pin velocity and u′ distributions off row 5 pin at 90deg, normalized by Vmax

Grahic Jump Location
Figure 11

Midline pressure coefficient distribution, row 5, ReDmax=30,000, 10,000, and 3000 comparing realizable k-ε predictions

Grahic Jump Location
Figure 12

Row 2 midline Nu∕ReDeff1∕2 as a function of angle, showing the effect of turbulence on pin heat transfer and compared with realizable k-ε, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 13

Cross-span velocity and u′ distributions, rows 1, 2, 3, and 5, normalized by Vmax, ReDmax=30,000

Grahic Jump Location
Figure 14

Cross-span velocity and u′ distributions, row 5 pin, normalized by Vmax

Grahic Jump Location
Figure 15

Cross-span distributions of u′∕Vmax, w′∕Vmax, rows 2, 3, and 5 for ReDmax=30,000

Grahic Jump Location
Figure 16

Endwall normal velocity profiles taken midline in row 5 (inner variables) at ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 17

Normal distributions of u′∕Vmax, v′∕Vmax, rows 2, 3, and 5 for ReDmax=30,000

Grahic Jump Location
Figure 18

Attenuation of low wave number v′ power spectra approaching endwall, row 5, ReDmax=30,000

Grahic Jump Location
Figure 19

Wall damping of v′2 approaching endwall, row 3, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 20

Wall damping of v′2 approaching endwall, row 5, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 21

Attenuation of low wave number w′ spectra approaching pin, row 5, ReDmax=30,000

Grahic Jump Location
Figure 22

Wall damping of w′2 approaching pin, row 5, ReDmax=30,000, 10,000, and 3000

Grahic Jump Location
Figure 23

Comparison of spanwise shear stress, u′w′¯∕(2∕3k)1∕2 and simple eddy viscosity model, w′0.38(z−5η)dW∕dz as a function of Z distance from pin

Grahic Jump Location
Figure 24

Comparisons between predictions of flow friction factor, UND data, and correlations

Grahic Jump Location
Figure 25

Comparisons between predictions of average array Nu, UND data, and correlations

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In