Influence of the thermal boundary condition on the heat transfer in a rib-roughened cooling channel using LES and RANS

Abstract

Internal cooling systems equipped with rib-roughened cooling ducts are used at turbine blades to refrigerate the metal by forced convection. The heat exchange between the walls of the cooling duct and the uid is sometimes modelled by Newton's law of cooling considering the heat transfer coe cient as a constant for a determinate study case. This assumption implies that the heat transfer is only a function of the temperature di erence between the wall temperature and the bulk ow temperature. The present study checks the in uence of the wall operating conditions over the heat transfer coe cient by simulating cases with di erent duct boundary conditions. Isother- mal and uniform heat ux rate boundary conditions with di erent discrete values are simulated using AVBP software. The mentioned simulations are also compared with other experimental and simulated results obtained by using Fluent software. The results show a increase in the heat transfer coe cient between the interface and the uid for the higher wall temperature when using an isothermal boundary condition and also for the higher heat ux rate when using an uniform heat ux rate boundary condition. A higher heat transfer coe cient is also seen when using the isothermal boundary condition compared to the use of an uniform heat ux rate boundary condition.