Date of Award

3-2006

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Aeronautics and Astronautics

First Advisor

Paul I. King, PhD

Abstract

Pulse detonation engines (PDE) rely on rapid ignition and formation of detonation waves. Because hydrocarbon fuels are composed typically of long carbon chains that must be reduced in the combustion process, it would be beneficial to create such reduction prior to injection of fuel into the engine. This study focused on PDE operation enhancements using dual detonation tube, concentric-counter-flow heat exchangers to elevate the fuel temperature up to supercritical temperatures. Variation of several operating parameters included fuel type (JP-8, JP-7, JP-10, RP-1, JP-900, and S-8), ignition delay, frequency, internal spiral length, and purge fraction. To quantify the performance, four key parameters examined were ignition time, deflagration to detonation transition time, detonation distance, and the percent of ignitions resulting in a detonation. In general, for all fuels except JP-10, increasing the fuel injection temperature decreased deflagration to detonation transition time and detonation distance, increased the percent of ignitions resulting in detonations (detonation percentage), and had no impact on ignition time. JP-10 was difficult to detonate, resulting in extremely poor performance. A minimum spiral length of 0.915 m (36 in) and a minimum purge fraction of 0.3 were determined. An increase in cycle frequency resulted in a decrease in deflagration to detonation transition time, but had little effect on ignition time and detonation distance. Analysis of ignition delay showed that 4 msec is the best ignition delay at high fuel injection temperatures, based on fire phase time and detonation percentage.

AFIT Designator

AFIT-GAE-ENY-06-M14

DTIC Accession Number

ADA450884

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