Pin Fin Surface Heat Transfer in Arrays of Oblong-shaped Pins

Open Access
Author:
Kirsch, Kathryn Louise
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Karen Ann Thole, Thesis Advisor
  • Horacio Perez Blanco, Thesis Advisor
  • Daniel Connell Haworth, Thesis Advisor
Keywords:
  • heat transfer
  • gas turbine
  • internal cooling
Abstract:
Gas turbines are a vital component in meeting modern society’s energy conversion needs and are found in a variety of applications, most generally in the areas of industrial power production and aircraft propulsion. Current gas turbine engines run at temperatures that far exceed the melting temperature of the components that run the engine. These components are subjected to extremely intense thermal and mechanical stresses. Advancements in the industry are directly tied to allowing even higher operating temperatures. To extend the lifetime of components in this hostile environment, advanced cooling technologies must be implemented, most especially in the first turbine stage, where temperatures are at their highest. One form of cooling technology can be found in inserting pin fin arrays into the internal passageways of turbine blades and vanes. These pin fins add surface area over which heat transfer can take place and promote turbulence within the channels, thereby increasing the heat transfer from the component. This study characterized the contribution to the heat transfer in an array of pin fins that comes from the pin surface itself. Oblong-shaped pins, with a constant height-to-diameter ratio of one, were studied. To gain an understanding of the heat transfer over the pin and correlated flow features through the array, the spanwise, streamwise and Reynolds number were varied. The oblongs were shown to have two regions of high heat transfer, one at the stagnation point of the pin and one immediately before the boundary layer on the surface transitioned to turbulence. When compared to the conventional cylindrical pin fins, the heat transfer from the oblong was approximately 30% lower; however, the pressure drop across the oblong array was between 60% and 50% lower than that across an array of cylindrical pins.