Design of Turbine Blade Internal Cooling: a Thermofluidic Study on the Influence of Varying Cooling Channel Numbers and Configurations

This paper explores the effect of varying the number and configuration of internal cooling channels on the thermal performance of gas turbine blades. The findings demonstrate the significance of this parameter for improving blade cooling efficiency. Actually, such a study is lacking in the currently available literature. Therefore, six internal cooling configurations were designed using Autodesk Inventor employing the real turbojet airfoil RS1S. The high-pressure gas turbine rotor blades were designed with an 11° twist angle in order to predict the actual behavior of the blade cooling under operating conditions. A series of numerical tests were carried out by coupling the CAD software with COMSOL Multiphysics. A conjugate heat transfer and computational fluid dynamics model were performed. Convective heat flux (CHF), temperature, Nusselt number, air velocity, Reynolds number, and friction force were evaluated for each studied case. The findings showed that adding a second cooling channel to the trailing edge improved the convective heat flux by 63%. On the other hand, creating a new cooling channel increased the blade’s thermal inertia, leading to a cooling limitation. It was also observed that hot spots on the blade surface can develop as a result of air thermal saturation due to extended residence time in the blade channels. In fact, the blade average temperature decreased by 8% using five disconnected channels rather than five serpentine channels. The blade temperature and CHF were reduced by 16 and 22%, respectively, as a result of adding a third channel in the blade mid-zone. Overall, this paper highlighted the potential for improving blade internal cooling through the careful optimization of the number and configuration of internal channels.