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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Numerical Simulation of Heat Transfer and Gas Dynamics in Warm Spray

Get access (open in a dialog) DOI: 10.1615/IHTC15.tps.009328
pages 9015-9023

Resumo

Warm spray is a modification of high velocity oxygen fuel spray. In this process, the high-temperature gas is accelerated to supersonic speed through a Laval nozzle followed by a straight barrel. By injecting gas at room temperature into the mixing chamber, the temperature of the gas can be controlled in a range of about 1000-2500 K, so that oxidation-free coatings are made from some oxygen and temperature-sensitive materials. The purpose of this paper is to establish a heat transfer and gas dynamics model for the supersonic flow. The model was solved using a computational dynamics code to predict heat transfer and fluid flow behavior in warm spray. The effects of the mixing gas (nitrogen) flow rates and the length of mixing chamber were investigated. It is shown that the optimal operating conditions in warm spray process can be achieved by adjusting the mixing gas flow rate. A dimensionless mixing length of 12 should be used to insure uniform temperature distribution at the exit of the mixing chamber.