Doctoral Dissertations

Abstract

"This dissertation focused on an investigation of small diameter hole drilling using abrasive slurry jet (ASJ) technology. The existing ASJ feed systems were reviewed and found inadequate to satisfy the requirements of an ASJ drill. A novel feed system was designed which improved on existing systems by resolving problems with the inability to perform stop/start operations and ensure precise metering of abrasive feed. This system met standards of consistency and evenness of feed required for machining aircraft component parts for Air Force Research Laboratory (AFRL). Theoretical and experimental analysis of the power of an ASJ stream yielded valuable design information that was then included in drilling tool design. The concept of introducing a swirl component in the nozzle before accelerating the slurry stream was used to design a Dispersed Abrasive Slurry jet (DASjet) nozzle. The influences of abrasive feed rate and pressure on the hole depth and diameter were studied. The effect of variation of the swirl angle on performance was found and an optimal angle identified. Material removal rates in air and under hole backpressure were determined. The loss in drilling performance when the drill operates against backpressure was overcome initially by the introduction of an air sheath around the jet. The cutting fluid and air shroud were then replaced with supercritical carbon dioxide. Supercritical CO₂ was shown to be a superior fluid medium to form the slurry jet because of the phase change which occurs at the nozzle orifice. Laboratory experiments conducted to validate this change successfully showed that this tool could drill holes to larger than two-inches in diameter, without nozzle rotation, and at rates of penetration of up to 400 ft/hour. As a result a novel drilling tool has been created for use in microhole drilling"--Abstract, page iii.

Advisor(s)

Summers, David A.

Committee Member(s)

Frimpong, Samuel
Galecki, Greg
Tien, Jerry C.
Gertsch, Leslie S.

Department(s)

Mining Engineering

Degree Name

Ph. D. in Mining Engineering

Sponsor(s)

National Energy Technology Laboratory (U.S.)

Comments

This work was partially carried out under funding from the U.S DOE-NETL Microhole Technology Development for Ken Oglesby, Impact Technologies, LLC.

Publisher

Missouri University of Science and Technology

Publication Date

Spring 2008

Pagination

xv, 222 pages

Note about bibliography

Includes bibliographical references (pages 216-221).

Rights

© 2008 Pradeep Nambiath, All rights reserved.

Document Type

Dissertation - Open Access

File Type

text

Language

English

Subject Headings

Drilling and boring machinery -- Design
Supercritical fluids
Abrasives

Thesis Number

T 10271

Print OCLC #

862973256

Electronic OCLC #

905905978

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