A numerical investigation of the cold spray process using underexpanded and overexpanded jets

S. Li, B. Muddle, Mahnaz Jahedi, J. Soria

Research output: Contribution to journalArticleResearchpeer-review

34 Citations (Scopus)


The impact velocity of particles during the cold spray process is crucial to the optimisation of coating quality and spraying costs. In the present investigation, both underexpanded and overexpanded impinging jets are employed to accelerate Aluminium particles towards a substrate. The impact velocity and angle statistics are generated by injecting polydisperse particles into the jet and the particle dynamics are characterised using the velocity and trajectories of the particles. The optimum particle size corresponding to the maximum impact speed is recast in terms of the Stokes number and shown to have a value of approximately one. Finally, a normal shock model is proposed which may be employed to estimate the particle impact speed using the nozzle exit conditions. It is shown that owing to artificial viscosity associated with the total variation diminishing scheme, this model tends to underestimate the speed.

Original languageEnglish
Pages (from-to)108-120
Number of pages13
JournalJournal of Thermal Spray Technology
Issue number1
Publication statusPublished - Jan 2012


  • fluid dynamics
  • modeling
  • modeling, computational fluid dynamics
  • modeling, finite element modelling
  • modeling, numerical model

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