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| Abstract No.: |
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Scheduled at:
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Friday, June 09, 2017, Hall 28 9:40 AM
Modeling & Simulation II
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| Title: |
The effect of substrate roughness on the heat transfer coefficient of an impinging cold spray air jet
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| Authors: |
Amirhossein Mahdavi* / University of Alberta, Canada
Andre McDonald / University of Alberta, Canada
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| Abstract: |
The effect of substrate roughness on the heat transfer coefficient and temperature distribution within the substrate during cold spraying was studied. The substrate was grit-blasted in order to roughen it. The roughened substrate was exposed to an under-expanding compressed hot air jet generated by a low-pressure cold spraying unit. An infrared camera was employed to collect the transient and steady-state surface temperature of the substrate during the impingement of the air jet. The Greens Function approach was employed to develop a mathematical model based on transient 2-D heat conduction to determine the temperature distribution within the substrate. The experimental data was coupled with the analytical model to predict the heat transfer coefficient between the impinging air jet and the roughened substrate. The results were compared to that obtained for a smooth substrate at different gas temperatures and stand-off distances. It was found that the heat transfer coefficient did not vary significantly between the roughened and smooth substrates at small stand-off distances. However, at higher stand-off distances, the predicted heat transfer coefficient for the roughened surface was slightly higher than that for the smooth substrate. It was concluded that any increased skin friction caused by the rough asperities on and turbulent flow over the grit-blasted substrate had negligible impact on the heat transfer coefficient of an impinging cold spray air jet.
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