Free Jet Impingement Heat Transfer of a High Prandtl Number Fluid Under Conditions of Highly Varying Properties

• Published in: Journal of heat transfer 1999-08, Vol.121 (3), p.592-597
• Main Authors: Leland, J. E, Pais, M. R
• Format: Article
• Language: English
• Subjects: Convection and heat transfer; Exact sciences and technology; Fluid dynamics; Fundamental areas of phenomenology (including applications); Heat flux; Heat losses; Heat transfer coefficients; Jets; Laminar flow; Nozzles; Nusselt number; Physics; Prandtl number; Reynolds number; Turbulent flows, convection, and heat transfer; Viscous flow
• ISSN: 0022-1481; 1528-8943
• DOI: 10.1115/1.2826020

An experimental investigation was performed to determine the heat transfer rates for an impinging free-surface axisymmetric jet of lubricating oil for a wide range of Prandtl numbers (48 to 445) and for conditions of highly varying properties (viscosity ratios up to 14) in the flowing film. Heat transfer coefficients were obtained for jet Reynolds numbers from 109 to 8592, nozzle orifice diameters of 0.51, 0.84 and 1.70 mm and a heated surface diameter of 12.95 mm. The effect of nozzle to surface spacing (1 to 8.5 mm), was also investigated. Viscous dissipation was found to have an effect at low heat fluxes. Distinct heat transfer regimes were identified for initially laminar and turbulent jets. The data show that existing constant property correlations underestimate the heat transfer coefficient by more than 100 percent as the wall to fluid temperature difference increases. Over 700 data points were used to generate Nusselt number correlations which satisfactorily account for the highly varying properties with a mean absolute error of less than ten percent.