Date of Graduation

2016

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Andrew C Nix

Committee Co-Chair

Patrick H Browning

Committee Member

Donald H Ferguson

Abstract

Rotating detonation engines (RDEs) present great potential for significant improvement in efficiency for land based power generation systems, in addition to aircraft propulsion devices. They offer the advantage of a net pressure gain across the combustor, as well as high exhaust temperatures and less entropy production due to detonative combustion. These improvements provide direct correlation to improved overall efficiency and thermal efficiency of gas turbine engines. RDEs surpass their conventional combustor counterparts in terms of their geometric size and simpler mechanical design. Among many areas of much needed research to further the technology readiness level (TRL) of RDEs, the inlet design is paramount to the successful operation of a rotating detonation engine. The inlet is one of the central impetuses behind current RDE research.;The existing inlet designs for RDEs in the research community are not optimized for maximum performance, yet are mostly used to operate research combustors. They are shown to induce high pressure drop, anywhere from 50-90%, and provide insufficient mixing for the inlet reactants. They also provide poor interaction between channel pressure fluctuations and detonation propagations. For these reasons, novel inlet design concepts are devised and tested in this work. The primary goal of the work is to design an inlet that is well isolated from the combustion channel, and is conducive to short interruption times of its refueling capability due to shockwave passes. This will precede the loss reduction efforts to the inlet. A combustor from the Air Force Research Lab (AFRL) serves as the baseline geometry for all testing conducted. A linear lab scale testing device, which is a scaled model of the full size cylindrical RDE to allow for lower flow rates and pressures to be used, has been developed for more simplified and rapid experimental testing of inlet concepts. Novel inlet geometries are designed and created using additive manufacturing techniques. Initial experiments are conducted on the baseline inlet and are used as comparison experimental results of new inlet designs. Geometric characteristics are leveraged for their acoustic and resonant properties in order to provide the highest backflow prevention. Experimental results for each design are presented and evaluated. High-speed Schlieren video is used to supplement the quantitative data reported, and is used to analyze the flow structures and interactions with detonation. Novel inlet concepts are presented that show capability to reduce the pressure influence of detonation by 1-2%, and improve the refueling time of the injectors. Improvements from the baseline inlet consist of improvements in backflow length by up to 60%, as well as reduction in recovery times from 20-30%.

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