Semester

Fall

Date of Graduation

2011

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Wade W Huebsch

Abstract

Discharge coefficients for irregular orifices have not been extensively studied and there exists a need to investigate these discharge properties and compare them to uniform orifices. The definition of an irregular orifice is an orifice profile that has no uniform shape or dimension such as that found in circular and square geometries. An irregular orifice could be present in a fluid system as a result of a puncture, rupture or fault. This research was conducted alongside a project involving inflatable structures to seal off an underground large scale piping system running below a waterway. An accurate prediction of the resulting flow rate in the case of a rupture is critical to determine the amount of time available to activate a protection system. Therefore, the motivation of this study was the determination of discharge coefficients for irregular orifices.;The objective in this thesis was the study of irregular orifices both as thin wall as well as extruded three dimensional orifices to gain an understanding for engineering failures. A co-objective was the general study of tube-type orifices discharging into the open atmosphere since previous tube orifice literature has primarily focused on in-pipe flow situations as an orifice plate.;An apparatus was built to test these orifices in a controlled environment under a constant head. The weighed discharge measured over time was factored into the discharge coefficient calculation as mass flow rate. Irregular orifices and tubes were created in the WVU MAE rapid prototype ABS printer allowing precise control of orifice shapes and profiles.;Selections of irregular and tube orifices were evaluated in this study. Tube orifice results (exiting to the atmosphere) are in agreement with pipe flow studies for l/d values ranging from 2.0 to 10.0. The discharge coefficient is drastically different in the l/d range from 0.0 to 2.0 where the behavior mimics a thin plate circular orifice as l/d approaches 2.0 with an average constant discharge coefficient of 0.63 in this region.;Irregular plate orifices resulted in a higher discharge coefficient across the orifice resulting in higher flow rates. This result can have significant impact on the calculations for a large scale piping breach. Extruding the irregular orifices to a tube orifice produced an interesting result; initially the extruded irregular orifice produces a maximum of 12.5% higher discharge coefficient, but after l/d∼2 the discharge coefficient behaves as a uniform tube orifice until convergence is achieved.

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