Supersonic Nozzle Flow Simulations for Particle Coating Applications: Effects of Shockwaves,Nozzle Geometry,Ambient Pressure,and Substrate Location upon Flow Characteristics |
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| Authors: | Jung-Jae Park Min-Wook Lee Sam S. Yoon Ho-Young Kim Scott C. James Stephen D. Heister Sanjeev Chandra Woon-Ha Yoon Dong-Soo Park Jungho Ryu |
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| Affiliation: | (1) Department of Mechanical Engineering, Korea University, Seoul, 136-713, Korea;(2) Thermal/Fluid Science and Engineering, Sandia National Laboratories, Livermore, CA 94551, USA;(3) School of Aeronautics and Astronautics, Purdue University, West Lafayette, IN 47907, USA;(4) Department of Mechanical and Industrial Engineering, University of Toronto, 5 King’s College Rd., Toronto, ON, Canada;(5) Functional Ceramics Research Group, Korea Institute of Materials Science, 66 Sangnam-Dong, Changwon, Kyungnam, 641-831, Korea; |
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| Abstract: | Characteristics of supersonic flow are examined with specific regard to nano-particle thin-film coating. Effects of shockwaves, nozzle geometry, chamber pressure, and substrate location were studied computationally. Shockwaves are minimized to reduce fluctuations in flow properties at the discontinuities across diamond shock structures. Nozzle geometry was adjusted to ensure optimal expansion (i.e., P exit = P ambient), where shock formation was significantly reduced and flow kinetic energy maximized. When the ambient pressure was reduced from 1 to 0.01316 bar, the nozzle’s diverging angle must be increased to yield the optimum condition of minimized adversed effects. Beyond some critical distance, substrate location did not seem to be a sensitive parameter on flow characteristics when P amb = 0.01316 bar; however, overly close proximity to the nozzle exit caused flow disturbances inside the nozzle, thereby adversely affecting coating gas flow. |
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