Session: Poster Session

Paper Number: 161898

Overall Cooling Effectiveness of Internally Cooled Additively Manufactured Blades 

Power generation gas turbine blades must utilize highly effective cooling schemes to withstand moderate heat loads for long operating times. Prior work indicates that gas turbines in the 5-10 MW range primarily utilize internal cooling to prevent further increase of aerodynamic losses that result from film cooling, but few studies focus solely on internal cooling. In this study, three additively manufactured internal cooling designs were tested in the 50 percent span section of the National Experimental Turbine (NExT) blade: a baseline cooling design with pin-fin arrays and rib turbulators, a double wall design with impingement jets and serpentine channels, and an incremental impingement design. The designs were tested in a high-speed linear cascade at exit Reynolds numbers ranging from 700,000 to 1,400,000 at an exit Mach of 0.8. In addition, freestream turbulence and build angle effects on cooling performance were studied. These results showed that, relative to the baseline design, the incremental impingement and double wall designs reduced cooling flow requirements by 50 and 25 percent, respectively, to achieve a desired overall cooling effectiveness. In addition, for a fixed coolant mass flow, increasing the exit Reynolds resulted in lower cooling effectiveness. However, when matched proportionately to heat load parameter, increasing the exit Reynolds has no significant effect. Increasing freestream turbulence resulted in lower cooling performance primarily at the leading edge and pressure side of the blades. Finally, manufacturing the airfoil at 45 degrees relative to its span direction resulted in less deviation from design intent compared to the vertical build, but lower overall cooling effectiveness.

Presenting Author: Rachel Ross Pennsylvania State University

Presenting Author Biography: Rachel Ross is a first year Mechanical Engineering master's student at Pennsylvania State University, conducting research in the Experimental and Computational Convection Laboratory (ExCCL) under Dr. Stephen Lynch.

Authors:

Rachel Ross Pennsylvania State University
Matthew Krull Pennsylvania State University
Stephen Lynch Pennsylvania State University
Matthew Searle National Energy Technology Laboratory, Department of Energy
Forrest Ames National Energy Technology Laboratory, Department of Energy
Douglas Straub National Energy Technology Laboratory, Department of Energy