Electronic Theses and Dissertations

Nadim Reza

Date

2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Mechanical Engineering

Committee Chair

John Hochstein

Committee Member

John Blanton

Committee Member

Daniel Foti

Committee Member

Thomas Hagen

Abstract

The motivation for the present research is to improve gas turbine efficiency by improving turbine blade trailing edge cooling. State-of-the-art trailing edge cooling deploys an array of pins inside a cavity in the trailing edge through which air passes to carry away heat. A novel pin shape is proposed in which a slot aligned with the bulk flow direction is added to the conventional pin shape in the center of each pin to increase the rate of heat transfer to the air and to decrease the pressure drop across the cavity.Computational simulations (using ANSYS FLUENT) of cooling flows through pin arrays of fixed pin diameter and fixed stagger angle with solidities of 25%, 35%, 45%, 55%, 65% were conducted for both the conventional circular cross-section and for the slotted cross-section with slot widths of 5%, 10%, 15%, 20%, and 25% of the pin diameter. The relative performance of these geometries was investigated for both fixed flow rate boundary conditions (Reynolds numbers of 6K, 10K, 20K, and 40K) and for fixed static pressure difference across the array (122 Pa and 1,017 Pa).For every geometry and boundary condition studied in this investigation, the heat transfer rate for the slotted-pin arrays was significantly higher than for the cylindrical pin arrays. With the exception of a single simulation using the narrowest slot width, the pressure drop across the array was lower for the slotted-pin arrays than for the cylindrical pin arrays. A unique optimal geometry cannot be identified because different figures of merit lead to selection of different geometries. Using heat transfer rate per unit volume as the figure of merit, the slotted-pin array resulted in as much as 15% more heat transfer than the comparable round pin array.

Comments

Data is provided by the student.

Library Comment

Dissertation or thesis originally submitted to ProQuest

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