Conjugate Heat Transfer Characterization in Cooling Channels

• Published in: Journal of thermal science Vol. 21; no. 3; pp. 286 - 294
• Main Authors: Cukurel, Beni, Arts, Tony, Selcan, Claudio
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science Press 01.06.2012
• Subjects: Classical and Continuum Physics; Engineering Fluid Dynamics; Engineering Thermodynamics; Heat and Mass Transfer; Nusselt数; Physics; Physics and Astronomy; 传导耦合; 传热特性; 共轭; 冷却通道; 强制对流; 燃气涡轮叶片; 边界条件; convection; infrared thermography; turbine cooling channel; conjugate heat transfer
• ISSN: 1003-2169; 1993-033X
• DOI: 10.1007/s11630-012-0546-1

Cooling technology of gas turbine blades, primarily ensured via internal forced convection, is aimed towards withdrawing thermal energy from the airfoil. To promote heat exchange, the walls of internal cooling passages are lined with repeated geometrical flow disturbance elements and surface non-uniformities. Raising the heat transfer at the expense of increased pressure loss; the goal is to obtain the highest possible cooling effectiveness at the lowest possible pressure drop penalty. The cooling channel heat transfer problem involves convection in the fluid domain and conduction in the solid. This coupled behavior is known as conjugate heat transfer. This experimental study models the effects of conduction coupling on convective heat transfer by applying iso-heat-flux boundary condition at the external side of a scaled serpentine passage. Investigations involve local temperature measurements performed by Infrared Thermography over flat and ribbed slab configurations. Nusselt number distributions along the wetted surface are obtained by means of heat flux distributions, computed from an energy balance within the metal domain. For the flat plate experiments, the effect of conjugate boundary condition on heat transfer is estimated to be in the order of 3%. In the ribbed channel case, the normalized Nusselt number distributions are compared with the basic flow features. Contrasting the findings with other conjugate and convective iso-heat-flux literature, a high degree of overall correlation is evident.