Date of Award

2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Aerospace Systems Engineering

Committee Chair

Phillip Ligrani

Committee Member

Jason Cassibry

Committee Member

Kirk Boehm

Research Advisor

Phillip Ligrani

Subject(s)

Turbomachines--Blades--Aerodynamics, Turbomachines--Blades--Fluid dynamics, Heat--Transmission

Abstract

Considered are two different film cooling hole configurations with round cylindrical holes and conical diffused holes, which are designated D5U and D5U-S, respectively. Associated data are provided as five of each type of holes are employed with transonic flow conditions along the upper pressure side of the blade at blowing ratios ranging from 1.70 to 3.78. Data associated with each cooling configuration are compared at similar values of blowing ratio BR and density ratio DR, which is generally in the vicinity of 1.5, to ensure that differences are a consequence of hole shape. Time- and spatially-resolved infrared camera measured data are analyzed to obtain spatially-resolved surface distributions of adiabatic film cooling effectiveness and heat transfer coefficient ratios. Line-averaged distributions are determined from these data along the pressure side rim, suction side rim, recess region, and trailing edge region, all with respect to the blade tip, as well as along the upper pressure side of the blade. Results from the present investigation show significant differences in cooling behavior and surface thermal protection for the two film cooling hole configurations. For example, cylindrical hole D5U results for the blade tip provide evidence that coolant which exits these holes travels around the corner edge of the blade and provides some coverage to the trailing edge region without providing much coverage to any other parts along the blade tip. Partial detachment of coolant accumulations is present due to local flow separation just downstream of the pressure side corner. In contrast, results associated with the conical diffused D5U-S holes provide evidence that the coolant film concentrations better adhere to blade surfaces, without significant detachment. The result is broader coolant surface coverage along the pressure side squealer rim and along upper pressure side surfaces. Overall, results of the present investigation demonstrate that hole geometry governs behavior of film cooling along transonic turbine blade surfaces. Conically diffused holes produce broader coolant coverage over most regions of the blade tip and upper pressure side. In contrast, the cylindrical holes direct coolant primarily toward the blade trailing edge.

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