Session: 12-09: Film Cooling Optimization and Novel Design

Paper Number: 154164

Thermal Performance Comparisons of Advanced Cooling Designs Under Engine Representative Conditions 

Novel turbine blade cooling geometries have conventionally been assessed using computational methods, simplified flat-plate geometries, or large-scale wind tunnels. These methods have the benefit of separating a turbine blade into individual cooling components to analyze how small changes in geometry impact the overall cooling performance of the test sample. While certain cooling geometries have demonstrated a beneficial heat transfer augmentation in simplified test environments, the question is whether these same augmentations can be achieved when the designs are integrated into a rotating turbine blade. In particular, packaged features can be subject to design constraints and corresponding manufacturing-driven limitations. The purpose of this study was to integrate cooling designs previously reported in the open literature–a tripod anti-vortex film-cooling hole and a densely packed diamond pedestal–into a true scale turbine blade to assess the overall cooling effectiveness of each geometry. The turbine blades were manufactured using traditional single-crystal casting approaches with laser ablated spanwise rows of cooling holes along the pressure and suction side surface. Each row of holes had one of three cooling hole geometries: round, shaped with a symmetric baseline 7-7-7 diffuser, or a tripod anti-vortex. An additional set of blades was also manufactured that contained an offset, densely-spaced diamond pedestal array in the TE section to allow comparisons with a baseline impingement slot feed design. All four unique blade designs were tested concurrently in a rainbow wheel configuration at engine-representative operating conditions in the Steady Thermal Aero Research Turbine (START) Lab. Blade surface temperatures were measured using thermal imaging methods over a range of cooling flow rates while computed tomography (CT) scans provided insight to how manufacturing variations impacted the mass flow rate through each blade. Results indicated that the anti-vortex tripod holes offered the most lateral spreading due to the advantageous wide coverage angle of the tripod design when compared with the baseline shaped hole design. The diamond pedestal TE section showed similar overall effectiveness to the baseline design with a decrease in needed mass flow rate to achieve the same blade temperature. In each case, the advanced hole designs and the diamond pedestal TE geometry benefits were compared with the results demonstrated in prior studies using simplified flat-plate geometries and large-scale wind tunnels to better quantify the relative impact of design trades, manufacturing effects, and true-scale rotating geometry influences.

Presenting Author: Nicholas Gailey Pennsylvania State University

Presenting Author Biography: Nick Gailey is a Ph.D. candidate at The Pennsylvania State University in the Department of Mechanical Engineering. He holds a Bachelor’s and Master’s degree in Mechanical Engineering from Penn State. His current research at the Steady Thermal Aero Research Turbine (START) Lab investigates channel and film cooling of additively manufactured components compared to traditional cast components. Previously, he has worked on IR imaging of rotating engine operated blades and heat flux implementation.

Authors:

Nicholas L. Gailey Pennsylvania State University
Emily E. Hartman The Pennsylvania State University
Michael D. Barringer The Pennsylvania State University
Reid A. Berdanier The Pennsylvania State University
Karen A. Thole The Pennsylvania State University
Allan Arisi Pratt & Whitney
Atul Kohli Pratt & Whitney