Effect of Reynolds Number and Property Variation on Fluid Flow and Heat Transfer in the Entrance Region of a Turbine Blade Internal-Cooling Channel

[摘要] Internal cooling is one of the effective techniques tocool turbine blades from inside. This internal cooling is achievedby pumping a relatively cold fluid through the internal-coolingchannels. These channels are fed through short channels placed atthe root of the turbine blade, usually called entrance regionchannels. The entrance region at the root of the turbine bladeusually has a different geometry than the internal-cooling channelof the blade. This study investigates numerically the fluid flowand heat transfer in one-pass smooth isothermally heated channelusing the RNGk−εmodel. The effect of Reynoldsnumber on the flow and heat transfer characteristics has beenstudied for two mass flow rate ratios (1/1and1/2) for thesame cooling channel. The Reynolds number was varied between10 000and50 000. The study has shown that the coolingchannel goes through hydrodynamic and thermal development whichnecessitates a detailed flow and heat transfer study to evaluatethe pressure drop and heat transfer rates. For the case ofunbalanced mass flow rate ratio, a maximum difference of8.9%in the heat transfer rate between the top and bottom surfacesoccurs atRe=10 000while the total heat transfer rate fromboth surfaces is the same for the balanced mass flow rate case.The effect of temperature-dependent property variation showed asmall change in the heat transfer rates when all properties wereallowed to vary with temperature. However, individual effects canbe significant such as the effect of density variation, whichresulted in as much as9.6% reduction in the heat transferrate.

[学科分类] 力学，机械学