Numerical investigation of the flows and heat transfer characteristics of internal cooling channels with separated ribs in gas turbine blades

Abstract

Gas turbine engines play a crucial role in numerous industrial domains, including power generation, aviation, and marine propulsion. One of the major challenges in designing gas turbine engines is managing the high temperature generated by the combustion process. Internal cooling is a commonly used technique to maintain the temperature of critical components, such as turbine blades, within a safe operating range. Rib turbulators are widely used in internal cooling systems to enhance heat transfer performance by promoting turbulence in the fluid flow. Nevertheless, the existence of a continuous rib within the cooling channel can result in elevated temperatures near the rib section, potentially diminishing the overall system efficiency. In response to this challenge, a new rib turbulator design, denoted as the “separated rib,” has been introduced to mitigate the high-temperature zone. Through the utilization of the passing-gap design in the separated rib configuration, the coolant flow passes through the gap, effectively eliminating the region of extreme heat and augmenting the secondary flow. Consequently, it results in a notable enhancement of heat transfer performance within the ribbed channel. The numerical simulations are performed by solving three-dimensional (3D) Reynolds-averaged Navier–Stokes equations using the commercial software ANSYS CFX. The working fluid is steam, and the heat transfer performance is evaluated in terms of the Nusselt number (Nu), friction factor (f), and thermal performance factor (TPF). The results show that the separated rib configuration has approximately 17.3% higher Nusselt number than the original ribbed configuration when the Reynolds number (Re) changes from 5000 to 60 000. The separated rib configuration consistently shows higher TPF values between about 1.6 and 1.9 than the original rib configuration, where TPF is smaller than 1.35. Furthermore, the heat transfer correlation related to the Reynolds number was developed to predict heat transfer performance. The heat transfer correlations align closely with the numerical simulation results, showing about 17.4% and 34.3% improvements in Nu and TPF, respectively, for our newly designed system compared to the old version.