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dc.contributor.advisorTilton, Nils
dc.contributor.authorParikh, Dhrupad
dc.date.accessioned2017-07-26T17:23:04Z
dc.date.accessioned2022-02-03T13:01:01Z
dc.date.available2017-07-26T17:23:04Z
dc.date.available2022-02-03T13:01:01Z
dc.date.issued2017
dc.identifierParikh_mines_0052N_11317.pdf
dc.identifierT 8326
dc.identifier.urihttps://hdl.handle.net/11124/171192
dc.descriptionIncludes bibliographical references.
dc.description2017 Summer.
dc.description.abstractUnderground tunneling involves the treatment and transportation of large amounts of soil using various conditioning agents. Foam, the most common conditioning agent, is injected into the soil at the cutter head of the tunnel boring machine. The foam transforms the excavated material into a deformable soil paste that provides a homogenous pressure to the surrounding ground, improves stability of the tunnel face, and minimizes friction and wear on metallic parts of a TBM. In the tunneling industry, foam is generated by flowing a mixture of air, water, and surfactant through a porous medium such as packed beads. Extensive studies have been done on the properties of conditioned soil; however, little literature exists on the mechanical system that generates the foam. This study focused on understanding the influence of the design and operating parameters of a foam generation system on different foam properties by replicating the foam generation process on a tunneling site. The foam generation system comprised of a foam generator filled with beads, a transport pipe to transfer the foam, and a pressure chamber in which we injected the foam under different pressures. Different system parameters were explored, such as size of bead fillings in the generator (1, 2, 3 mm), lengths of foam generator (110, 200, 400 mm), length (1, 3, 5 m) and diameter (6.3, 9.5, 12.7 mm) of foam transport pipes, and chamber pressure (1, 3, 5 bar). The air and liquid mass flow rates were varied as 9.5 to 49 slpm and 0.3 to 2.2 slpm respectively. Foam properties such as the foam bubble size distribution, stability, and compressibility were investigated. Based on the experimental study it was found that the average bubble diameter decreased with decrease in bead size. The pore-scale mixing governed the bubble diameter for 3 mm bead size, while the pore size played a dominant role incase of 1 and 2 mm beads. The chamber pressure also had a significant influence on the foam bubble diameter and foam stability. With the increase in the chamber pressure, the bubble diameter decreased, and the foam stability increased. Some preliminary experiments are conducted to investigate if foam could be generated without a foam generator, and how would the bubble size vary through a transport pipe. It was observed that foam could be generated without a foam generator if longer transport pipes are used.
dc.format.mediumborn digital
dc.format.mediummasters theses
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2017 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subjectfoam generation system
dc.subjectpressure drop
dc.subjecttunnel boring machine
dc.subjectfoam properties
dc.subjectbead size
dc.subjectsuperficial velocities
dc.titleExperimental study of pressure drop and bubble size in a laboratory scale compressed air foam generation system
dc.typeText
dc.contributor.committeememberMooney, Michael A.
dc.contributor.committeememberNeeves, Keith B.
thesis.degree.nameMaster of Science (M.S.)
thesis.degree.levelMasters
thesis.degree.disciplineMechanical Engineering
thesis.degree.grantorColorado School of Mines


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