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dc.contributor.authorMaisto, Pietroen_US
dc.date.accessioned2016-02-18T07:00:28Z
dc.date.available2016-02-18T07:00:28Z
dc.date.issued2014-08-26en_US
dc.identifier.othervt_gsexam:2378en_US
dc.identifier.urihttp://hdl.handle.net/10919/64835
dc.description.abstractThe work described focuses on characterization of fluorescence dye-doped polystyrene latex particles (PSLs) dispersed in air as a candidate for advanced flow diagnostic techniques for applications in wind tunnels. PSLs with mean diameter on the order of 1 μm were provided by collaborators at NASA Langley Research Center and measurements of simultaneous Mie scattering and laser induced fluorescence (LIF) signals were obtained with the goal of providing a capability for velocity and scalar flow measurements. Three organic fluorescent dyes, Rhodamine B (RhB), Dichlorofluorescein (DCF), and Kiton Red (KR), were doped into PSLs and studied in benchtop experiments. A major interest in the present research is the application of safe dyes, thus DCF and KR are of particular interest, while RhB is used as a benchmark. The study is broken up into two major elements: response of the particles to continuous wave (CW) excitation, and response to pulsed excitation. The former was examined for mean LIF imaging and single-point single-shot measurements, the latter for planar single-shot measurements. The LIF signal has several potential uses, though the primary interest herein is the reduction of flare from wind tunnel walls which occurs at the laser excitation wavelength and the use of the fluorescence signal for sensing temperature. It is demonstrated that the LIF signal under CW excitation may be used for velocimetry with the laser-Doppler velocimetry technique, thus effective in filtering out the laser flare in the vicinity of wind tunnel models or walls. A two-band LIF technique was also demonstrated for one of the DCF batches, indicating that the technique effectively removes interfering inputs such as particle diameter and dye concentration variation. Temperature measurement uncertainties are estimated based upon the variance measured for the two-band LIF intensity ratio and the achievable dye temperature sensitivity, indicating that particles developed to date may provide about 12.5 degrees C precision. Pulsed excitation with an Nd:YAG laser at about 200mJ/pulse at 532 nm yield no fluorescence above the detection threshold of the cameras used from the DCF batch examined. However, a batch doped with Kiton Red 620 was shown to provide sufficient intensity of LIF for single-shot planar measurements such as PIV via planar LIF. The KR batch also exhibited highly non-uniform yield of fluorescence signal on a particle-to-particle basis - this despite a highly uniform Mie scattering signal. Given the uniform Mie signal and a relatively narrow Gaussian distribution of the particles size, a possible mechanism is mentioned for the LIF non-uniformity as lasing within individual particles due to whispering gallery mode resonance.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.rightsThis Item is protected by copyright and/or related rights. Some uses of this Item may be deemed fair and permitted by law even without permission from the rights holder(s), or the rights holder(s) may have licensed the work for use under certain conditions. For other uses you need to obtain permission from the rights holder(s).en_US
dc.subjectLaser Diagnosticsen_US
dc.subjectFluid Dynamicsen_US
dc.subjectLIFen_US
dc.subjectParticlesen_US
dc.titleExperimental analysis and prospective flow diagnostic applications for fluorescence dye-doped microparticlesen_US
dc.typeThesisen_US
dc.contributor.departmentAerospace and Ocean Engineeringen_US
dc.description.degreeMaster of Scienceen_US
thesis.degree.nameMaster of Scienceen_US
thesis.degree.levelmastersen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineAerospace Engineeringen_US
dc.contributor.committeechairLowe, Kevin Todden_US
dc.contributor.committeememberBruno, Claudioen_US
dc.contributor.committeememberSchetz, Joseph A.en_US


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