Identifier

etd-11112008-182237

Degree

Master of Science in Mechanical Engineering (MSME)

Department

Mechanical Engineering

Document Type

Thesis

Abstract

A mathematical model is formulated for assessing quasi-one-dimensional gas dynamics occurring within axis-symmetric explosively actuated valves. The model describes complete valve operation and accounts for pressure-dependent explosive combustion within an actuator, compressible product gas flow within the actuator, through a small port, and into and within a gas expansion chamber. The gas dynamic waves induce piston motion at the terminal end of the expansion chamber which is needed for valve operation. The model is mathematically posed as an initial-boundary-value problem in terms of generalized coordinates to facilitate numerical computations on a domain that volumetrically expands due to combustion and piston motion. The model equations are numerically integrated using a total variation diminishing (TVD), high resolution shock capturing method. Key objectives of this work are to characterize the influence of gas dynamic waves on device operation and performance, including the pyrotechnic shock transmitted to the valve's supporting structure. For a baseline valve configuration, predictions give results that agree with experimental data for the expansion chamber pressurization rate, and both piston stroke time and velocity. The model is used to assess how variations in port cross-sectional area, explosive mass, geometric size, and other system parameters affect performance. This sensitivity analysis has shown, in all cases considered, that the pressurization rates of the actuator and the expansion chamber are the main factors that effect valve performance. High actuator pressurization rates are necessary for complete explosive combustion while high expansion chamber pressurization rates are necessary for rapid, monotonically increasing piston velocity that is desirable in practice.

Date

2008

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Keith A. Gonthier

DOI

10.31390/gradschool_theses.2431

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