Date of Award

3-21-2019

Document Type

Thesis

Degree Name

Master of Science in Aeronautical Engineering

Department

Department of Aeronautics and Astronautics

First Advisor

Mark F. Reeder, PhD

Abstract

With the increased demand for lighter, more fuel efficient and smaller gas turbine engines, the impetus to reduce the weight and size of the turbine has become apparent. One approach to reduce this weight is to reduce the number of blades in the turbine. However, to maintain power output, each blade must be capable of supporting a greater amount of lift. While several high-lift turbine profiles have been detailed in literature, most of these profiles have increased endwall losses, despite their desirable mid-span characteristics. To mitigate this endwall loss, a number of active and passive flow approaches have been studied and reported. The current effort documents significant manipulation and reduction in strength of endwall flow features via active control in the AFRL Low Speed Wind Tunnel Test Facility. The manipulation of the pressure side leg of the horseshoe vortex, formed at the leading edge of the turbine profile, has been shown to reduce overall pressure loss near the endwall in certain active flow control conditions. The active flow took the form of a localized low-momentum pulsed jet directly under the pressure side leg of the horseshoe vortex. Total pressure loss measurements have been collected and mapped at six planes within and beyond the passage. To supplement the total pressure loss measurements, high speed stereographic particle image velocimetry data were collected to study the effects of localized forcing of the endwall flow structure. The combination of the velocity measurements at several planes throughout the passage and the total pressure loss measurements led to a deeper understanding of the fluid dynamic mechanisms responsible for the reduction in endwall losses.

AFIT Designator

AFIT-ENY-MS-19-M-202

DTIC Accession Number

AD1072586

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