Publication Date

2012

Document Type

Thesis

Committee Members

Haibo Dong (Advisor), Greg Minkiewicz (Committee Member), Rory Roberts (Committee Member)

Degree Name

Master of Science in Engineering (MSEgr)

Abstract

The Office of Security of Defense's Assured Fuels Initiative has recently been pressing for a single fuel battle space. This endeavor requires modifying many of the vehicle power plants currently in operation throughout the Armed Forces. The RQ-7 Shadow, an unmanned aerial vehicle (UAV) utilized by the Marine Corp and Army for reconnaissance purposes, is powered by UEL's AR741 rotary engine and functions on aviation fuel. One effort underway has been focused on developing this rotary engine system to operate on heavy fuels using direct injection technology and charge stratification. Although the rotary engine has many advantages over standard reciprocating engines, providing a reliable ignition source for the stratified charge within the sweeping combustion chamber presents challenges. This work made effort to compensate for those challenges by utilizing a pilot flame ignition system. The system incorporated a micro-diesel injector and spark plug recessed within an ignition cavity along the housing of the rotary engine. The pilot flame ignition approach was thoroughly evaluated by conducting a parametric study using computational methods to simulate the combustion process. Gambit meshing software was used to build the 3D rotary engine mesh. ANSYS Fluent was used to formulate and apply the various numerical models describing the combustion phenomena. And lastly, JMP software was used to perform a response surface analysis in effort to determine the optimal parameter values for the ignition system. The goal of the parametric study was to maximize power output and likewise minimize specific fuel consumption. A total of thirty one cases were performed to complete the study. For the rotary engine operating at 6000rpm an optimal solution was successfully realized within the design space. The rotary engine model generated 5.313 horsepower (HP) for the complete cycle of one chamber. The overall equivalency ratio allocated in the combustion chamber for the simulations was 0.55. This resulted in a specific fuel consumption of 0.395 lb/hp-h. The study not only provided evidence to confirm the profitable use of a pilot flame ignition system applied to the direct injection stratified charge rotary engine (DISCRE), but also provided multiple insights on the design and operation of such a system.

Page Count

110

Department or Program

Department of Mechanical and Materials Engineering

Year Degree Awarded

2012

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