2026-09-19T11:06:05Zhttps://dspace.mit.edu/server/oai/requestoai:dspace.mit.edu:1721.1/781882022-01-13T07:54:36Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023
Alexandra H. Techet.
Scharfman, Barry Ethan
Massachusetts Institute of Technology. Dept. of Mechanical Engineering.
Massachusetts Institute of Technology. Department of Mechanical Engineering
2013-03-28T18:12:45Z
2013-03-28T18:12:45Z
2012
2012
http://hdl.handle.net/1721.1/78188
830347915
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Spray flows are a difficult problem within the realm of fluid mechanics because of the complicated interfacial physics involved. Complete models of sprays having even the simplest geometries continue to elude researchers and practitioners. From an experimental viewpoint, measurement of dynamic spray characteristics is made difficult by the optically dense nature of many sprays. Flow features like ligaments and droplets break off the bulk liquid volume during the atomization process and often occlude each other in images of sprays. In this thesis, two important types of sprays are analyzed. The first is a round liquid jet in a cross flow of air, which applies, for instance, to fuel injection in jet engines and the aerial spraying of crops. This flow is studied using traditional high-speed imaging in what is known as the bag breakup regime, in which partial bubbles that look like bags are formed along the downstream side of the liquid jet due to the aerodynamic drag exerted on it by the cross flow. Here, a new instability is discovered experimentally involving the presence of multiple bags at the same streamwise position along the jet. The dynamics of bag expansion and upstream column wavelengths are also investigated experimentally and theoretically, with experimental data having found to generally follow the scaling arguments predicted by the theory. The second flow that is studied is the atomization of an unsteady turbulent sheet of water in air, a situation encountered in the formation and breakup of ship bow waves. To better understand these complicated flows, the emerging light field imaging (LFI) and synthetic aperture (SA) refocusing techniques are combined to achieve three-dimensional (3D) reconstruction of the unsteady spray flow fields. A multi-camera array is used to capture the light field and raw images are reparameterized to digitally refocus the flow field post-capture into a volumetric image. These methods allow the camera array to effectively "see through" partial occlusions in the scene. It is demonstrated here that flow features, such as individual droplets and ligaments, can be located in 3D by refocusing throughout the volume and extracting features on each plane.
by Barry Ethan Scharfman.
S.M.
161 p.
eng
Massachusetts Institute of Technology
M.I.T. theses are protected by
copyright. They may be viewed from this source for any purpose, but
reproduction or distribution in any format is prohibited without written
permission. See provided URL for inquiries about permission.
http://dspace.mit.edu/handle/1721.1/7582
Mechanical Engineering.
Analysis of multiphase fluid flows via high speed and synthetic aperture three dimensional imaging
Thesis
application/pdf
false
Publication
unknown
unknown
<Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="3b9968e3-0230-4821-8741-b775b38f6cf4">
<Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type>
<Language>eng</Language>
<Title>Analysis of multiphase fluid flows via high speed and synthetic aperture three dimensional imaging</Title>
<PublishedIn>
<Publication>
</Publication>
</PublishedIn>
<PublicationDate>2012</PublicationDate>
<Authors>
<Author>
<DisplayName>Scharfman, Barry Ethan</DisplayName>
<Affiliation>
<OrgUnit>
</OrgUnit>
</Affiliation>
</Author>
</Authors>
<Editors>
</Editors>
<Publishers>
<Publisher>
<DisplayName>Massachusetts Institute of Technology</DisplayName>
<OrgUnit />
</Publisher>
</Publishers>
<License>http://dspace.mit.edu/handle/1721.1/7582</License>
<Keyword>Mechanical Engineering.</Keyword>
<Abstract>Spray flows are a difficult problem within the realm of fluid mechanics because of the complicated interfacial physics involved. Complete models of sprays having even the simplest geometries continue to elude researchers and practitioners. From an experimental viewpoint, measurement of dynamic spray characteristics is made difficult by the optically dense nature of many sprays. Flow features like ligaments and droplets break off the bulk liquid volume during the atomization process and often occlude each other in images of sprays. In this thesis, two important types of sprays are analyzed. The first is a round liquid jet in a cross flow of air, which applies, for instance, to fuel injection in jet engines and the aerial spraying of crops. This flow is studied using traditional high-speed imaging in what is known as the bag breakup regime, in which partial bubbles that look like bags are formed along the downstream side of the liquid jet due to the aerodynamic drag exerted on it by the cross flow. Here, a new instability is discovered experimentally involving the presence of multiple bags at the same streamwise position along the jet. The dynamics of bag expansion and upstream column wavelengths are also investigated experimentally and theoretically, with experimental data having found to generally follow the scaling arguments predicted by the theory. The second flow that is studied is the atomization of an unsteady turbulent sheet of water in air, a situation encountered in the formation and breakup of ship bow waves. To better understand these complicated flows, the emerging light field imaging (LFI) and synthetic aperture (SA) refocusing techniques are combined to achieve three-dimensional (3D) reconstruction of the unsteady spray flow fields. A multi-camera array is used to capture the light field and raw images are reparameterized to digitally refocus the flow field post-capture into a volumetric image. These methods allow the camera array to effectively "see through" partial occlusions in the scene. It is demonstrated here that flow features, such as individual droplets and ligaments, can be located in 3D by refocusing throughout the volume and extracting features on each plane.</Abstract>
<Access xmlns="http://purl.org/coar/access_right"
>
</Access>
</Publication>