Aerothermodynamics of turbine blade trailing edge cooling

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2018
Tunçel, Tuğba
It is known that the thermal efficiency of gas turbines strongly depends on the turbine entry temperature of the working fluid. This has resulted in increased turbine working temperatures, and peak temperatures in advanced gas turbines have been well above maximum allowable metal temperatures for quite some time. For turbine blades to survive while operating beyond these material temperature limits, internal and external cooling techniques have been developed. Due to structural and aerodynamic restrictions, improving trailing-edge cooling methods creates a challenge for the designers. In modern turbine blades, pressure side cutbacks with film cooling slots stiffened with lands and pin fins embedded in passages are used to cool trailing edges. In literature, thermal improvements obtained by slots, lands and similar internal structures have been investigated in detail since the main purpose has been to promote cooling. But, when the performance of a gas turbine is considered, aerodynamic enhancements are as important as thermal performance. Regarding that, this thesis focuses on both aerodynamic and thermal aspects of a turbine blade trailingedge section cooling. The internal structure studied consists of staggered arrays of pins, and lands and airfoil-shaped blockages in front of the trailing edge slots right at the exit. The pins used are of cylindrical, elliptical, and airfoil shape, and have different sizes. A study using Computational Fluid Dynamics (CFD) was performed to investigate the flow structure and heat transfer both inside the passage and outside in the vicinity of trailing-edge slots. With the goal of choosing an optimal pin fin configuration that is aerothermodynamically more advantageous for slot film cooling, this thesis provides a thorough investigation that would be of interest to the turbine designers.

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Citation Formats
T. Tunçel, “Aerothermodynamics of turbine blade trailing edge cooling,” M.S. - Master of Science, Middle East Technical University, 2018.