Technique for imaging ablation-products transported in high-speed boundary layers by using naphthalene planar laser-induced fluorescence

dc.contributor.advisorClemens, Noel T.en
dc.contributor.committeeMemberRaman, Venkatramananen
dc.creatorLochman, Bryan Johnen
dc.date.accessioned2010-12-20T18:52:16Zen
dc.date.available2010-12-20T18:52:16Zen
dc.date.available2010-12-20T18:52:24Zen
dc.date.issued2010-08en
dc.date.submittedAugust 2010en
dc.date.updated2010-12-20T18:52:24Zen
dc.descriptiontexten
dc.description.abstractA new technique is developed that uses planar laser-induced fluorescence (PLIF) imaging of sublimated naphthalene to image the transport of ablation products in a hypersonic boundary layer. The primary motivation for this work is to understand scalar transport in hypersonic boundary layers and to develop a database for validation of computational models. The naphthalene is molded into a rectangular insert that is mounted flush with the floor of a Mach 5 wind tunnel. The distribution of naphthalene in the boundary layer is imaged by using PLIF, where the laser excitation is at 266 nm and the fluorescence is collected in the range of 320 to 380 nm. To investigate the use of naphthalene PLIF as a quantitative diagnostic technique, a series of experiments is conducted to determine the linearity of the fluorescence signal with laser fluence, as well as the temperature and pressure dependencies of the signal. The naphthalene fluorescence at 297 K is determined to be linear for laser fluence that is less than about 200 J/m². The temperature dependence of the naphthalene fluorescence signal is found at atmospheric pressure over the temperature range of 297K to 525K. A monotonic increase in the fluorescence is observed with increasing temperature. Naphthalene fluorescence lifetime measurements were also made in pure-air and nitrogen environments at 300 K over the range 1 kPa to 40 kPa. The results in air show the expected Stern-Volmer behavior with decreasing lifetimes at increasing pressure, whereas nitrogen exhibits the opposite trend. Preliminary PLIF images of the sublimated naphthalene are acquired in a Mach 5 turbulent boundary layer. Relatively low signal-to-noise-ratio images were obtained at a stagnation temperature of 345 K, but much higher quality images were obtained at a stagnation temperature of 380 K. The initial results indicate that PLIF of sublimating naphthalene may be an effective tool for studying scalar transport in hypersonic flows.en
dc.description.departmentAerospace Engineeringen
dc.format.mimetypeapplication/pdfen
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-08-1922en
dc.language.isoengen
dc.subjectAblationen
dc.subjectFluorescenceen
dc.subjectPLIFen
dc.subjectPlanar laser-induced fluorescenceen
dc.subjectNaphthaleneen
dc.subjectLIFen
dc.subjectLaser-induced fluorescence signalen
dc.subjectStern-Volmeren
dc.titleTechnique for imaging ablation-products transported in high-speed boundary layers by using naphthalene planar laser-induced fluorescenceen
dc.type.genrethesisen
thesis.degree.departmentAerospace Engineering and Engineering Mechanicsen
thesis.degree.disciplineAerospace Engineeringen
thesis.degree.grantorUniversity of Texas at Austinen
thesis.degree.levelMastersen
thesis.degree.nameMaster of Science in Engineeringen

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