Graduation Semester and Year

2019

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Aerospace Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Frank Lu

Abstract

The feasibility of fluidic valves for use in detonation-based engines was studied numerically. The fluidic valve acted by shutting off reactant flow through the high pressure behind detonation waves propagating past the valve opening. The valve which featured a plenum cavity was mounted to the side of a pulsed detonation engine, an arrangement that allowed the valve to be characterized under a sustained operation. A series of different cavity lengths were studied. Further, a numerical study of the high-frequency fluidic valve was conducted by using a two-dimensional reactive Euler solver. A 19–step elementary mechanism was employed for the stoichiometric oxyhydrogen combustion. Two conditions, named as blocked cavity and air injection, were studied. Insights into the complex behavior of the shock wave interactions within the fluidic valve cavity were obtained. The pressure histories of the incident shock and the subsequent reflections within the cavity were tracked via wave diagrams. The wave diagrams indicated that the longer cavities induced reflections for a longer duration in both the blocked and air-injection configurations, with the latter showing more complicated flows. The numerical trends were similar in terms of non-dimensional pressure and interruption time, agreeing with the experimental results of Peace et al. (2014) but disagreeing with earlier single-shot results. Further simulations, by changing the position of the fluidic valve with respect to the thrust wall of the detonation tube reiterated the importance of fluidic valve location. The numerical findings include the backflow plots which represent the required refueling time with respect to the arrival of the fresh combustible mixture inside the detonation tube.

Keywords

Detonation, PDE, Fluidic valve, Numerical

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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