Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 36 for “"Laser Diagnostics"”.
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Novel Multifunctional Laser Diagnostics
… seeking to advance the state-of-the-art in laser based, multi-functional, non-invasive diagnostic systems. The results of the work have contributed to the development of methodological generic approaches to the development of devices using light to detect and analyse biomarkers relevant to …
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Laser diagnostics of non-equilibrium plasmas
… plasma represents requires sophisticated diagnostics. Such diagnostics have to be species specific and provide spatial and time resolved information about the quantities of interest, such as temperature (vibrational and rotational), product concentration and energy deposition. Given these …
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Laser diagnostics of soot in hydrocarbon diffusion flames
Driven by the demand for soot-free combustion, laser-based diagnostic techniques on soot have been developing since the late 1980s. One of these techniques is line-of- sight extinction, which is a fast, low-cost, and quantitative method to investigate the soot volume fraction in flames. However, …
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Reactive flow visualization through high-speed optical laser diagnostics
… was demonstrated using temporally-resolved laser diagnostics to visualize: 1) The turbulent flow field with particle image velocimetry (PIV); and 2) the distribution of combustion radicals, by planar laser-induced fluorescence (PLIF). This allows for the visualization of the flame surface …
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Three Dimensional Laser Diagnostics for Turbulent Flows and Flames
… of this dissertation thus is to investigate such diagnostics and demonstrate their capability and limitations in a range of turbulent flows/flames. To accomplish this goal, this dissertation developed and evaluated the following three diagnostic methods: tomographic chemiluminescence (TC), …
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Investigation of stagnation-flow diamond-forming flames using advanced laser diagnostics
… were measured using three-photon-excitation laser-induced fluorescence (LIF). The CARS measurements showed peak flame temperatures of 3300 K, approximately 200 K above the adiabatic equilibrium temperature for these flames. Temperatures were measured to within approximately 50 $\mu$m of the …
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Development of high-speed laser diagnostics for the study of advanced propulsion systems
… this effort that the progressing capabilities of laser diagnostics open new possibilities of exploring the chemistry and fluid dynamics of complex reacting flows. The primary objective of this study is to develop and apply kHz-rate planar imaging to further our understanding of ignition and flame …
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Experimental Investigation of a Lean, Premixed Gas Turbine Combustor Using Advanced Laser Diagnostics
… and stabilization were studied using planar laser-induced fluorescence of the hydroxyl radical. Four operating conditions were examined---two equivalence ratios, 0.6 and 0.7, and two combustor pressure drops, 3% and 5%. Time-resolved images were acquired at two axial locations for each test …
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Laser Diagnostics Applied to Lean Premixed Swirling Flames - Simultaneous Flow Field and Scalar Measurements
… of lean premixed swirling flames. Various laser-based optical diagnostic techniques were used to collect information under different operational conditions. Combined flow- and scalar field measurements were performed at high repetition rates for detailed studies of the turbulent flames. A …
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Simulating high flux solar radiation and assessing its influence on a sooty flame
… temperature in a laminar sooty flame. Detailed laser diagnostics was performed on a laminar sooty flame with and without the irradiance of CSR, because laser diagnostics are demonstrated to hold the advantages of being non-intrusive, lower interferences and of being applicable to environments …
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Kelvin-Helmholtz Instability in Magnetized Plasma
… physics. In one type of experiment, with a laser produced plasma expanding in an external magnetic field, we observed the Kelvin-Helmholtz instability growing at the plasma-field boundary, where a velocity gradient perpendicular to the plasma velocity forms. The magnetized Kelvin-Helmholtz …
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Experimental investigations into high-altitude relight of a gas turbine
… a ground-based test facility. The application of laser diagnostics presents particular difficulties due to the large quantities of liquid fuel that impinge on the combustor walls during relight. Advances are made in the application of planar laser-induced fluorescence (PLIF) to monitor fuel …
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Spectrum and conversion efficiency measurements of suprathermal electrons from relativistic laser plasma interactions
… Confinement Fusion (ICF) that uses a petawatt laser to ignite a hot spot in precompressed fuel. The laser delivers its energy into relativistic electrons at the critical surface of the blowoff plasma. These electrons must propagate to the fuel core and deliver their energy to a hot spot. …
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Model-based spectral inference in noisy physical time series: applications in laser linewidth estimation and precision magnetometry
… settings – narrow-linewidth semiconductor lasers and spin-precession-based magnetometry – pose inverse problems that traditional methods struggle with due to low signal-to- noise ratios, nonstationary dynamics, and convolutional measurement effects. Spectral estimation is crucial in …
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Laser induced incandescence imaging for the investigation of soot formation in laminar flames
This work has been aimed at applying laser induced incandescence imaging for the measurement of soot concentration within a variety of novel flame sources and setups. Laser induced incandescence (LII) is an optical technique used in laser diagnostics to measure soot volume fraction and estimate …
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On the Use of Laser-Induced Incandescence for Soot Diagnostics: From Theoretical Aspects to Applications in Engines
The laser-induced incandescence technique (LII) is a laser-based diagnostic technique for measurements of soot volume fraction and particle size. The technique relies on detection of incandescent light from soot particles heated to around 4000 K using nanosecond laser pulses. A theoretical model …
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Modeling Three Reacting Flow Systems with Modern Computational Fluid Dynamics
… gas turbine combustor using advanced laser diagnostics. However, these data were taken by different investigators at BYU over the course of 10 years, and the data were scattered through several publications, theses, and dissertations. This third project was to compile these data into a …
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Study of multi-component fuel premixed combustion using direct numerical simulation
… commonly used to visualize heat release rate in laser diagnostics are found to be inadequate for the multi-component fuel flame, and alternative markers are proposed. Finally, some popular mean reaction rate closures are tested for the multi-component fuel flame. Significant differences are …
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Velocity, temperature, and electric field measurements on a plasma-assisted hydrogen diffusion flame
A plasma-assisted hydrogen diffusion flame, denoted as a coaxial AC DBD burner, was designed and analyzed for comparisons with simulations and to better understand the coupling of the plasma and reacting flow. Emission, PLIF, and schlieren imaging of the burner revealed three distinct operating …
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Multi-dimensional Flow and Combustion Diagnostics
… transient in time. Therefore, multidimensional diagnostics that are capable of resolving such spatial and temporal dynamics have long been desired; and the purpose of this dissertation is to investigate three such diagnostics both for the fundamental study of flow and combustion processes and …
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