Abstract

To satisfy the ever increasing loading and thermal demands of axial gas turbines, there is a need for improved prediction and design tools. Knowledge of the heat transfer and aero loading is a crucial part of improving design tools to increase the performance of future gas turbines.
Experiments were performed at The Ohio State University Gas Turbine Laboratory measuring pressure, temperature, and heat flux for a fully cooled high-pressure transonic turbine stage operating at design corrected conditions. The single-stage turbine consists of a rainbow rotor containing three different cooling hole shapes: round, fan, and advanced. Cooling air is supplied to the forward purge, blade film cooling, and aft purge flow paths. During the test matrix, the mass flow of cooling supply was varied to evaluate the rotor cooling performance at several cooling conditions.
Measurements of the blade internal channel pressures are compared among four different cooling mass flow rates to highlight differences caused by blowing ratio for the various cooling hole geometries. Blade aero-loading at mid-span and heat flux at multiple different locations are analyzed on time-accurate, time-averaged, and ensemble-averaged bases. In addition, data from the hub region of the nozzle-guide vane endwall and blade platform highlight some of the unsteady interactions governing purge flow injection. Ensemble-average data shows the variations of heat flux and pressure loading during each vane pass, and reveals where heat flux and pressure fluctuations are synchronized as well as regions where they are not. The heat transfer and pressure characteristics presented in this study will guide engineers in the prediction of heat transfer and aid in the design of the next generation of highly efficient turbomachines.