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RESEARCH PAPERS

Transport of Particulates in an Internal Cooling Ribbed Duct

[+] Author and Article Information
Anant Shah, Danesh K. Tafti

High Performance Computational Fluids, Thermal Sciences and Engineering Lab, Mechanical Engineering Department, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061

Earlier studies were done with a development time of 23.5 nondimensional time units. No difference was found in the measured particle statistics with the shorter development time.

This is a reasonably good approximation for erosion of ductile materials.

J. Turbomach 129(4), 816-825 (Aug 04, 2006) (10 pages) doi:10.1115/1.2720509 History: Received August 02, 2006; Revised August 04, 2006

A ribbed square duct (Pe=10, eDh=0.10) subjected to sand ingestion is studied using large-eddy simulations (LES). Particle sizes of 10μm, 50μm, and 100μm with nondimensional response times (normalized by friction velocity and hydraulic diameter) of 0.06875, 1.71875, and 6.875, respectively are considered. The calculations are performed for a nominal bulk Reynolds number of 20,000 under fully-developed conditions. Distributions of impingement density, impingement velocities and angles, together with fractional energy transfer are presented for each surface. It is found that about 40% of the total number of 10micron particles are concentrated in the vicinity (within 0.05 Dh) of the duct surfaces, compared to 25–30% of the 50 and 100micron particles. The 10micron particles are more sensitive to the primary and secondary flow velocities than the larger particles. While the 10micron particles exhibit high energy transfer to the surface near the rib side-wall junction and immediately upstream of the rib, the larger particles exhibit more uniform distributions. The largest fraction of incoming particulate energy is transferred to the front face of the rib and is between one to two orders of magnitude larger than the other surfaces. As particle size increases, substantial particle energy is also transferred to the back face of the rib by particles bouncing off the front face and carrying enough momentum to impinge on the back face of the preceding rib.

Copyright © 2007 by American Society of Mechanical Engineers
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References

Figures

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Figure 11

Average impingement angles at the bottom wall: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 1

Comparison of mean streamwise velocity predicted by the current model with particle statistics by Wang and Squires (14). Particles compared: 70μm copper, 50μm glass, and 28μm Lycopodium.

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Figure 2

Computational domain nondimensionalized by the hydraulic diameter (Dh)(11)

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Figure 3

(a) Mean streamline distribution in the z-symmetry plane. Reattachment occurs at 4.1e downstream of rib. The leading edge eddy extends between 0.8 and 0.9e upstream of rib. (b) Mean lateral or spanwise flow velocity (wb) in the vicinity of the smooth wall. Taken from (11).

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Figure 4

Time evolution of particle distribution near duct surfaces

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Figure 5

Number of particles impinging on the side wall in 1.3ms: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 6

Impact velocity on the side wall: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 7

Impact angle on the side wall: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 8

Fractional energy transfer to side wall (ψ×106): (a) 10μm; (b) 50μm; (c) 100μm

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Figure 9

Number of particles impinging on the ribbed wall in 1.3ms: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 10

Average impingement velocities at the ribbed wall: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 12

Fractional energy transfer to the ribbed wall (ψ×106): (a) 10μm; (b) 50μm; (c) 100μm

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Figure 13

Number of particles impinging the front surface of the rib in 1.3ms: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 14

Average impingement velocities on the front surface of the rib: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 15

Average impingement angles on the front surface of the rib: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 16

Fractional energy transfer to the front face of the rib (ψ×106): (a) 10microns; (b) 50microns; (c) 100microns

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Figure 17

Number of particles impinging on the back surface of the rib in 1.3ms: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 18

Average impingement velocities on the back surface of the rib: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 19

Average impingement angles on the back surface of the rib: (a) 10μm; (b) 50μm; (c) 100μm

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Figure 20

Fractional energy transfer to back face of the rib (ψ×106): (a) 10microns; (b) 50microns; (c) 100microns

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