Date of Award

9-9-2008

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD

Abstract

Fueling the core airflow of a circular or elliptical scramjet combustor cross-section often requires intrusive geometries. Intrusive geometries can distribute the fuel evenly across the combustor cross-section and act as a flameholder for the fuel/air mixture. Compared to conventional transverse or angled wall injection, intrusive geometries allow easier penetration into the core combustor airflow and reduced fuel injection pressures. The design and testing of an intrusive pylon geometry for scramjet combustor fueling is the subject of this research. Three pylon configurations are compared: a basic pylon, a ramp pylon, and an alternating wedge pylon. All three pylon configurations exhibit the same frontal area and inject fuel parallel to the combustor airflow with long, thin rectangular injection ports (thin film fueling). However, the three pylon configurations incorporate different aft shapes to facilitate fuel/air mixing. A cold flow fuel injection study is accomplished to compare mixing capabilities and total pressure losses of the three pylon configurations. Four experimental techniques are used: 1) computational fluid dynamics, 2) aerothermal probing, 3) Raman spectroscopy, and 4) planar laser induced fluorescence. The ramp and alternating wedge pylons show decisive increases in mixing capability compared to the basic pylon. They also exhibit a slight increase in total pressure loss compared to the basic pylon.

AFIT Designator

AFIT-DS-ENY-08-02

DTIC Accession Number

ADA487085

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