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Title: An experimental and numerical investigation of the heat transfer and thermal history of spray deposited tubular billets
Author: Sperring, T. P.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1998
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This thesis is concerned with heat transfer phenomena in the spray deposition process. It is concerned with the deposition process as developed by Osprey Metals, Neath, UK. It focuses on the thermal history of tubular preform production. A former was constructed using the same dimensions as the tubular billet produced at Osprey Metals, and this was instrumented to measure heat transfer coefficients all over its surface. This heat transfer was measured using especially designed heat transfer meters which fitted into the former. The results from the experimental programme show that the heat transfer around the preform varies in a smooth curve suggesting that there is a Coanda effect present. Heat transfer was also highest closest to the preform substrate and the freshly deposited metal. FLUENT, a commercial computational fluid dynamics program, was used to model the fluid flow in the chamber. Both two and three dimensional models were built using body fitted coordinates. Discussion on the theory behind the package as well as details on the individual models used are presented. Results from this work are examined and compared to the results from the experimental programme. Good correlation was found between the three dimensional computation fluid dynamics and the results from the experimental programme with regard to the fluid flow in the process. Heat transfer trends were also well predicted in both two and three dimensional cases. Finally, two thermal network programs were written to describe the thermal history in the preform during deposition. These were used to calculate the thermal history of the entire tubular billet by looking at two dimensional planes perpendicular to each other. The experimental and CFD data was incorporated into this model through heat transfer coefficients. Results from this work give a thermal history of the billet from initialisation to a fully deposited tubular billet and this work showed the relative sensitivity of the thermal history with different physical parameters. It was shown that the substrate preheating and preparation were of prime importance in this respect.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available