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Modelling Knudsen number effects in suspension high velocity oxy fuel thermal spray

Chadha, S.; Jefferson-Loveday, R.; Hussain, T.

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Authors

S. Chadha

R. Jefferson-Loveday

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TANVIR HUSSAIN TANVIR.HUSSAIN@NOTTINGHAM.AC.UK
Professor of Coatings and Surface Engineering



Abstract

Suspension high velocity oxy fuel thermal spray is a system characterized by supersonic velocities and length scales of particles of the order of nm – µm. As the effects of rarefication become significant the assumptions within the continuum models begin to collapse, the effects of rarefication can be evaluated through the flow Knudsen number. Modifications to the numerical modelling must be made to incorporate the effects of rarefaction. This study looks to include the effects of rarefication into the computational fluid dynamics (CFD) models for the suspension high velocity oxy-fuel (SHVOF) thermal spray process. A model for the heat transfer coefficient that take into account the Knudsen and Mach number effects is employed. Finally, the Ranz-Marshall correlation for the Nusselt number is compared to the Kavanau correlation and a compressible Nusselt number correlation. The model is validated through comparisons of particle temperatures which are obtained from two colour pyrometry measurements using a commercially available Accuraspray 4.0 diagnostic system. This study shows that there is a significant improvement in the prediction of inflight particle temperatures when accounting for the effects of compressibility and the effects of rarefication on the Nusselt number.

Citation

Chadha, S., Jefferson-Loveday, R., & Hussain, T. (2020). Modelling Knudsen number effects in suspension high velocity oxy fuel thermal spray. International Journal of Heat and Mass Transfer, 152, https://doi.org/10.1016/j.ijheatmasstransfer.2020.119454

Journal Article Type Article
Acceptance Date Jan 29, 2020
Online Publication Date Feb 12, 2020
Publication Date 2020-05
Deposit Date Feb 13, 2020
Publicly Available Date Mar 29, 2024
Journal International Journal of Heat and Mass Transfer
Print ISSN 0017-9310
Electronic ISSN 0017-9310
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 152
Article Number 119454
DOI https://doi.org/10.1016/j.ijheatmasstransfer.2020.119454
Keywords Mechanical Engineering; Condensed Matter Physics; Fluid Flow and Transfer Processes
Public URL https://nottingham-repository.worktribe.com/output/3956997
Publisher URL https://www.sciencedirect.com/science/article/pii/S0017931019349956
Additional Information This article is maintained by: Elsevier; Article Title: Modelling Knudsen number effects in suspension high velocity oxy fuel thermal spray; Journal Title: International Journal of Heat and Mass Transfer; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.ijheatmasstransfer.2020.119454; Content Type: article; Copyright: © 2020 The Authors. Published by Elsevier Ltd.