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Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department

Agricultural and Biosystems Engineering

First Advisor

Daniel Humberg

Abstract

A new abrasive blasting system was designed to satisfy the unique design requirements of an abrasive applicator to be used in a novel, post-emergence, selective weed control method in organic cropping systems. Specifically, the desire to eliminate the pressurized reservoir and wear of the nozzle throat that plagues commercial pressure blast designs led to an entirely new abrasive blasting system composed of a perfectly expanded nozzle to accelerate an airstream, followed by entrainment of abrasive in a larger constant-diameter section where additional ambient air is also entrained to minimize the effects of friction. Extensive theoretical models were implemented during the design of each component in the abrasive blasting system including the oil-flooded, rotary screw air compressor, the perfectly expanded nozzle, and the abrasive entrainment section in order to aid in design decisions. The performance of the concept nozzle assembly was quantified with experimental results of its abrasive velocity, pattern width, and air and abrasive consumptions and compared to experimental results obtained with a conventional pressure blast nozzle. The effect of operating parameters including blasting pressure and abrasive loading ratio were also quantified. Particle velocity was measured using a double-disk apparatus to compute their time of flight. The experimental results validated the new theoretical models proposed. The abrasive velocities produced by the new blasting system fell short of the pressure blast nozzle but exceeded the typical abrasive velocities of comparable suction blast systems and the threshold velocity needed to control weed growth.

Library of Congress Subject Headings

Abrasives
Weeds -- Control
Blasting Machines

Description

Includes bibliographical references (leaves 178-180)

Format

application/pdf

Number of Pages

343

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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