Conjugate heat transfer from a discrete-source heated plate by offset jet impingement

Abstract

Convection/conduction simulations have been performed to determine flow and heat transfer phenomena in steady-state, for a plate carrying few embedded discrete heaters, exposed to by a turbulent offset cooling jet. This configuration is relevant, for example, in thermal design of vehicle body segments in aerodynamics conditions: when realized in certain alloys, their configuration will be determined based their discrete structural state prompted by supplied electrical heating. In order to approach an appropriate thermal design of the plate and obtain their precise state, the space of geometric and operating variables needs to be explored by a thorough parametric study based on the governing momentum and energy equations.In this paper, the interaction between the impinging boundary layer and the conductive effects produced by such discrete heaters is explored, giving rise to a conjugate heat transfer situation. With a flexible notation for discretized heating and temperature-dependent conduction, dimensionless heat transfer is discussed spanning the entire range of design parameters. Results report considerable variation in heat transfer: as an example, air jet over polypropylene plates brings about peak Nusselt numbers between 2000 and 4000 for an inclined configuration at Re≈1×106 based on nozzle width, with related strong temperature gradients that must be addressed during design, depending on discrete heaters' configuration and properties; whereas for alumina plates the peak Nusselt numbers fall down between 600 and 750, featuring much smoother temperature variations and consequent more stable structural states.