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Research Papers: Multiphase Flows

Computational and Experimental Studies on Cavity Filling Process by Cold Gas Dynamic Spray

[+] Author and Article Information
Hidemasa Takana1

Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japantakana@paris.ifs.tohoku.ac.jp

HongYang Li2

Department of Mechanical Systems and Design, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

Kazuhiro Ogawa

Fracture and Reliability Research Institute, Tohoku University, 6-6 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

Tsunemoto Kuriyagawa

Department of Nanomechanics, Graduate School of Engineering, Tohoku University, 6-6 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan

Hideya Nishiyama

Institute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan

1

Corresponding author.

2

Present address: Mitsui Chemicals, Inc.

J. Fluids Eng 132(2), 021302 (Feb 04, 2010) (9 pages) doi:10.1115/1.4000802 History: Received December 16, 2008; Revised November 16, 2009; Published February 04, 2010; Online February 04, 2010

Time-dependent computational simulations on cavity filling process by cold gas dynamic spray and powder jet deposition process ranging from microscale to macroscale were carried out in order to give an insight for their advanced applications to joining, crack repair, and dental treatment. Shock wave appears in front of the substrate due to underexpansion of jet and in-flight particles interact with the shock wave before their impact. The relation between shock wave, cavity configuration, and particle in-flight behavior in supersonic jet has been discussed in detail. Based on numerical and experimental studies, it was found that when the shock wave covers up the cylindrical cavity, the cavity cannot be filled at all by deposited powders. Moreover, under the condition of shock wave appearing inside the cylindrical cavity, conical deposition was formed due to the secondary back flow jet along the cavity side wall. By adopting conical cavity, cavity can be filled completely resulting from the suppression of the secondary back flow jet along the cavity side wall.

Copyright © 2010 by American Society of Mechanical Engineers
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References

Figures

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Figure 1

Splat profile of aluminum particle impinging on a steel substrate

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Figure 2

Schematic Illustration of powder jet deposition system for advanced dental treatment: nozzle inner diameter is 1.0 mm and nozzle-substrate distance is 1.7 mm

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Figure 3

Schematic illustration of cold gas dynamic spray system: nozzle inner diameters are 8.5 mm at the inlet, 2.5 mm at the throat, and 4.8 mm at the exit; nozzle-substrate distance is 10.0 mm

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Figure 4

Axial evolutions of velocities of 800 nm and 2 μm particles

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Figure 5

Dependence of particle size on particle velocities at nozzle exit and cavity bottom in microspace

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Figure 6

(a) Laser sheet visualization of particle-laden jet in powder jet deposition process and (b) comparison of computational particle velocity with PIV measurement result

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Figure 7

Particle trajectories and Mach number distributions for (a) dcav/dnoz=0.5, (b) 1.0, and (c) 1.5

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Figure 8

Particle impact velocities as a function of particle diameter for dcav/dnoz=0.5, 1.0, and 1.5

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Figure 9

(a) Particle impact velocities and impact positions and (b) created coating profile for dcav/dnoz=0.5

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Figure 10

(a) Particle impact velocities and impact positions and (b) created coating profile for dcav/dnoz=1.5

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Figure 11

Comparison with experimental results for (a) static pressure and (b) static temperature

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Figure 12

Comparison with experimental results for total pressure on flat plate or at cavity bottom

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Figure 15

Cross-sectional photos of cavities after 20 s of spraying: (a) spherical cavity and (b) conical cavity; pictures are shown with computed gas velocity vectors at the beginning of spray

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Figure 14

Cross-sectional photos of cylindrical cavities after 20 s of spraying (a) dcav/dnoz=1.0 and (b) 1.5: pictures are shown with computed gas velocity vectors after coating formation

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Figure 13

Cross-sectional photos of cylindrical cavities with computed gas velocity vectors at the beginning of spray (a) dcav/dnoz=0.5, (b) 1.0, and (c) 1.5

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