Date of Award

9-2021

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

James L. Rutledge, PhD

Abstract

To improve thermal efficiency and reduce fuel consumption, gas turbine engines typically operate at increasingly higher turbine inlet temperatures--well in excess of turbine blade material limits--and film cooling schemes are normally employed to reduce metal temperatures within acceptable limits and prevent structural failure. Cooling requirements vary across a blade surface, but there currently exists no means by which coolant temperatures can be locally adjusted to facilitate optimized usage across a blade. Ranque-Hilsch vortex tubes were investigated as a means of adjusting coolant temperatures solely by fluidic means, induced by the phenomenon of temperature separation. Analytical frameworks were developed to determine adiabatic and overall effectiveness in the presence of multiple coolant temperatures and validated via experiment. Through the integrated application of experimental, analytical, and computational investigations, the parameters which govern temperature separation were identified as well as the proper means of scaling temperature separation and the underlying physics behind the mechanism of temperature separation. Heat transfer characteristics of vortex tubes were determined and vortex tube performance near engine conditions was modeled. Findings were synthesized to estimate the net effect on turbine blades, including adiabatic wall temperatures and thermally conductive metal surfaces, and was found under some circumstances to be operationally significant.

AFIT Designator

AFIT-ENY-DS-21-S-093

DTIC Accession Number

AD1151640

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