The Effect of Single-Sided Ribs on Heat Transfer and Pressure Drop Within a Trailing Edge Internal Channel of a Gas Turbine Blade

Abstract

Convective cooling in a gas turbine blade internal trailing edge channel is often insufficient at the sharp trailing edge. This study examines convective heat transfer and pressure drop within a simplified nonrotating trailing edge channel. The internal passage has been modeled as a right triangular channel with a 9 deg angle sharp corner. A copper plate was heated from underneath via a uniform heat flux heater and examined via infrared thermography for two cases: smooth wall and single-sided ribbed wall. Nonuniformity in the heat flux due to conduction is corrected by a Reynolds-averaged Navier–Stokes (RANS) conjugate heat transfer calculation, which was validated by the mean velocity, friction factor, and temperature fields from experiments and large eddy simulation (LES). Nusselt number distributions illustrate that surface heat transfer is increased considerably with ribs and coupled with the vortices in the flow. Heat transfer at the sharp corner is increased by more than twofold due to ribs placed at the center of the channel due to secondary flow. The present single-sided ribbed channel utilizes secondary flow toward the corner and is presumed to have better thermal performance than a dual-sided ribbed channel. Thus, it is important to set the appropriate rib length within the channel.