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dc.contributor.authorBrooks, Donald Rayen
dc.date.accessioned2017-06-13T19:43:50Zen
dc.date.available2017-06-13T19:43:50Zen
dc.date.issued2014-04-15en
dc.identifier.otheretd-04252014-170021en
dc.identifier.urihttp://hdl.handle.net/10919/78089en
dc.description.abstractFluid dynamicists are always in need of innovative instruments for flow velocity measurements. An ideal instrument would be non-intrusive, have a very fine spatial resolution as well as a very fine temporal resolution, be able to measure three-components of velocity, and be compact. Through recent advancements, laser Doppler velocimetry can now meet all of those requirements making it an important part of aerodynamicist's research toolbox. The first paper presented in this manuscript style thesis explains the development of an advanced three-velocity component, spatially-resolving laser-Doppler velocimetry (LDV) system for highly resolved velocity measurements in situations with limited optical access. The new instrument, a next generation version of the previously developed 'comprehensive' LDV technology, enables measurements of three components of velocity and particle position in the axial direction all through a single transceiving lens. Described here is the design process and the final design for the 'compact, comprehensive' LDV (Comp²LDV). The probe was designed to achieve ± 10 micron root-mean-square uncertainties in axial particle position, which combined with the long measurement volume, allow researchers to obtain a three-velocity-component velocity statistics profiles over a span of approximately 1.5mm without the need for traversing. Results from measurements in a flat plate turbulent boundary layer very near the wall have compared favorably to data from previous studies. The second paper focuses on the motion and evolution of coherent structures in supersonic jet flows and how that relates to the intense noise the flows generate. As a preliminary study to experimentally address these relationships, novel non-intrusive measurements using two-component laser Doppler velocimetry (LDV) have been conducted at exceptionally high data rates to lend insight into the statistical behavior of noise-generating flow structures. A new heated supersonic jet facility has been constructed to provide supersonic flow at total temperatures ratios (T₀/Tₐ) up to 3. In the present work, the instrumentation is validated via comparison of LDV measurements along the centerline of a screeching cold jet with microphone and high-speed shadowgraph results. Reynolds stress spectra are presented for an over-expanded case (nozzle pressure ratio of 3.2) of a design Mach number 1.65 nozzle operated cold (T₀/Tₐ = 1). A preliminary study was then conducted in the near-nozzle shear layer, up to x/d = 4.0, at design nozzle pressure ratio (4.58) and total temperature ratio of 2.0. Results are presented for Reynolds stress time-delay correlations and power spectra at Re_d = 1.1M for this case. The stream-wise Reynolds normal stress spectra are compared with published spectral behavior reported by other researchers, indicating a similar spectral shape in the downstream stations as previously measured with LDV and hot wire anemometry for cold jets, but which differ in shape from density-based techniques.en
dc.language.isoen_USen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectlaser flow diagnosticsen
dc.subjectlaser-Doppler velocimetryen
dc.subjectlaser-Doppler anemometryen
dc.subjectTurbulenceen
dc.subjectspectral measurementsen
dc.subjectspatially resolvingen
dc.subjectboundary layersen
dc.subjectsupersonic jetsen
dc.subjectheated jetsen
dc.subjectnon-intrusive flow measurementen
dc.subjectflow measurement techniquesen
dc.titleDevelopment of Specialized Laser Doppler Velocimeters for High Resolution Flow Profile and Turbulence Spectral Measurementsen
dc.typeThesisen
dc.contributor.departmentAerospace and Ocean Engineeringen
dc.description.degreeMaster of Scienceen
thesis.degree.nameMaster of Scienceen
thesis.degree.levelmastersen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.disciplineAerospace and Ocean Engineeringen
dc.contributor.committeechairLowe, K. Todden
dc.contributor.committeememberNg, Wing Faien
dc.contributor.committeememberSimpson, Roger L.en
dc.type.dcmitypeTexten
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04252014-170021/en
dc.date.sdate2014-04-25en
dc.date.rdate2014-06-05en
dc.date.adate2014-06-05en


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