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A Laser Induced Fluorescence Technique For Measurement Of Slot Injected Fluid Concentration Profiles In A Plate Turbulent Boundary Layer
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Book Synopsis A Laser-Induced Fluorescence Technique for Measurement of Slot-Injected Fluid Concentration Profiles in a Plate Turbulent Boundary Layer by : T. A. Brungart
Download or read book A Laser-Induced Fluorescence Technique for Measurement of Slot-Injected Fluid Concentration Profiles in a Plate Turbulent Boundary Layer written by T. A. Brungart and published by . This book was released on 1990 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique for measuring near instantaneous concentration profiles of a fluid injected through a narrow inclined slot at the wall into a high unit Reynolds turbulent boundary layer is discussed. The concentration profiles are determined by measuring the light intensity emitted from a fluorescent dye premixed into the injectant flow as the injectant convects through an excitation laser beam. The fluorescence intensity is quantified by an electronically shuttered single stage microchannel plate image intensifier coupled to a linear photodiode array. This high resolution technique is being used to study the diffusion of injected polymer solutions away from the near wall region in a flat plate turbulent boundary layer where these solutions are effective in reducing drag. Keywords: Reynolds turbulent boundary layer. (aw).
Book Synopsis A Fluorescence Technique for Measurement of Slot Injected Fluid Concentration Profiles in a Turbulent Boundary Layer by :
Download or read book A Fluorescence Technique for Measurement of Slot Injected Fluid Concentration Profiles in a Turbulent Boundary Layer written by and published by . This book was released on 1990 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique for measuring near instantaneous concentration profiles of a fluid injected through a narrow inclined slot at the wall into a high unit Reynolds number flat plate turbulent boundary layer is discussed. The concentration profiles are determined by measuring the light intensity emitted from a fluorescent dye, premixed into the injectant flow, as the injectant convects through an excitation laser beam. The fluorescence intensity is quantified by an electronically shuttered single stage microchannel plate image intensifier coupled to a linear photoidode array. This instrumentation provided the high spatial and temporal resolution required for these boundary layer concentration profile measurements. The laser induced fluorescence technique is being used to study the diffusion of injected polymer solutions away from the near wall region of the boundary layer where these solutions are effective in reducing drag. The diffusion of slot injected water has also been examined and the present results are in excellent agreement with previous studies.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Annual Index by :
Download or read book Government Reports Annual Index written by and published by . This book was released on 1990 with total page 1316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Government Reports Announcements & Index by :
Download or read book Government Reports Announcements & Index written by and published by . This book was released on 1991-05 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Preprints for the ... Symposium on Turbulence by :
Download or read book Preprints for the ... Symposium on Turbulence written by and published by . This book was released on 1990 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Strategies for Planar Laser-induced Fluorescence Thermometry in Shock Tube Flows by : Ji Hyung Yoo
Download or read book Strategies for Planar Laser-induced Fluorescence Thermometry in Shock Tube Flows written by Ji Hyung Yoo and published by Stanford University. This book was released on 2011 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis was motivated by the need to better understand the temperature distribution in shock tube flows, especially in the near-wall flow regions. Two main ideas in planar laser-induced fluorescence (PLIF) diagnostics are explored in this thesis. The first topic is the development of a single-shot PLIF diagnostic technique for quantitative temperature distribution measurement in shock tube flow fields. PLIF is a non-intrusive, laser-based diagnostic technique capable of instantaneously imaging key flow features, such as temperature, pressure, density, and species concentration, by measuring fluorescence signal intensity from laser-excited tracer species. This study performed a comprehensive comparison of florescence tracers and excitation wavelengths to determine the optimal combination for PLIF imaging in shock tube flow applications. Excitation of toluene at 248nm wavelength was determined to be the optimal strategy due to the resulting high temperature sensitivity and fluorescence signal level, compared to other ketone and aromatic tracers at other excitation wavelengths. Sub-atmospheric toluene fluorescence yield data was measured to augment the existing photophysical data necessary for this diagnostic technique. In addition, a new imaging test section was built to allow PLIF imaging in all regions of the shock tube test section, including immediately adjacent to the side and end walls. The signal-to-noise (SNR) and spatial resolution of the PLIF images were optimized using statistical analysis. Temperature field measurements were made with the PLIF diagnostic technique across normal incident and reflected shocks in the shock tube core flow. The resulting images show uniform spatial distribution, and good agreement with conditions calculated from the normal shock jump equations. Temperature measurement uncertainty is about 3.6% at 800K. The diagnostic was also applied to image flow over a wedge. The resulting images capture all the flow features predicted by numerical simulations. The second topic is the development of a quantitative near-wall diagnostic using tracer-based PLIF imaging. Side wall thermal boundary layers and end wall thermal layers are imaged to study the temperature distribution present under constant pressure conditions. The diagnostic technique validated in the shock tube core flow region was further optimized to improve near-wall image quality. The optimization process considered various wall materials, laser sheet orientations, camera collection angles, and optical components to find the configuration that provides the best images. The resulting images have increased resolution (15[Mu]m) and are able to resolve very thin non-uniform near-wall temperature layers (down to 60[Mu]m from the surface). The temperature field and thickness measurements of near-wall shock tube flows under various shock conditions and test gases showed good agreement with boundary layer theory. To conclude this thesis, new applications and future improvements to the developed PLIF diagnostic technique are discussed. These suggested refinements can provide an even more robust and versatile PLIF imaging technique capable of measuring a wider range of flow conditions near walls.
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Journal of Current Laser Abstracts by :
Download or read book Journal of Current Laser Abstracts written by and published by . This book was released on 1990 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Quantitative Measurements of Ablation-products Transport in Supersonic Turbulent Flows Using Planar Laser-induced Fluorescence by : Christopher Stanley Combs
Download or read book Quantitative Measurements of Ablation-products Transport in Supersonic Turbulent Flows Using Planar Laser-induced Fluorescence written by Christopher Stanley Combs and published by . This book was released on 2015 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: A recently-developed experimental technique based on the sublimation of naphthalene, which enables imaging of the dispersion of a passive scalar using planar laser-induced fluorescence (PLIF), is applied to a Mach 5 turbulent boundary layer and a NASA Orion capsule flowfield. To enable the quantification of naphthalene PLIF images, quantitative fluorescence and quenching measurements were made in a temperature- and pressure-regulated test cell. The test cell measurements were of the naphthalene fluorescence lifetime and integrated fluorescence signal over the temperature range of 100 K to 525 K and pressure range of 1 kPa to 40 kPa in air. These data enabled the calculation of naphthalene fluorescence yield and absorption cross section over the range of temperatures and pressures tested, which were then fit to simple functional forms for use in the calibration of the PLIF images. Quantitative naphthalene PLIF images in the Mach 5 boundary layer revealed large-scale naphthalene vapor structures that were regularly ejected out to wall distances of approximately y/ [delta] = 0.6 for a field of view that spanned 3 [delta] to 5 [delta] downstream of the trailing edge of the naphthalene insert. The magnitude of the calculated naphthalene mole fraction in these structures at y/ [delta] = 0.2 ranged from approximately 1-6% of the saturation mole fraction at the wind tunnel recovery temperature and static pressure. An uncertainty analysis showed that the uncertainty in the inferred naphthalene mole fraction measurements was ± 20%. Mean mole fraction profiles collected at different streamwise locations were normalized by the mole fraction measured at the wall and a characteristic height of the scalar boundary layer, causing the profiles to collapse into one "universal" mole fraction profile. Two-dimensional fields of naphthalene mole fraction were also obtained simultaneously with velocity by using particle image velocimetry (PIV) and PLIF. The images show large-scale naphthalene vapor structures that coincide with regions of relatively low streamwise velocity. The covariance of naphthalene mole fraction with velocity indicates that an ejection mechanism is transporting low-momentum, high-scalar-concentration fluid away from the wall, resulting in the protrusions of naphthalene vapor evident in the instantaneous PLIF images. Lastly, naphthalene PLIF was used to visualize the dispersion of gas-phase ablation products on a scaled Orion capsule model at four different angles of attack at Mach 5. High concentrations of scalar were imaged in the capsule recirculation region. Additionally, intermittent turbulent structures were visualized on the heat shield surface, particularly for the 12° and 52° AoA cases.
Book Synopsis Laser-saturated Fluorescence Measurements in Laminar Sooting Diffusion Flames by : Changlie Wey
Download or read book Laser-saturated Fluorescence Measurements in Laminar Sooting Diffusion Flames written by Changlie Wey and published by . This book was released on 1993 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical is known to be one of the most important intermediate species in the combustion processes. The hydroxyl radical has also been considered a dominant oxidizer of soot particles in flames. In this investigation the hydroxyl concentration profiles in sooting diffusion flames were measured by the laser-saturated fluorescence (LSF) method. The temperature distributions in the flames were measured by the two-line LSF technique and by thermocouple. In the sooting region the OH fluorescence was too weak to make accurate temperature measurements. The hydroxyl fluorescence profiles for all four flames presented herein show that the OH fluorescence intensities peaked near the flame front. The OH fluorescence intensity dropped sharply toward the dark region of the flame and continued declining to the sooting region. The OH fluorescence profiles also indicate that the OH fluorescence decreased with increasing height in the flames for all flames investigated. Varying the oxidizer composition resulted in a corresponding variation in the maximum OH concentration and the flame temperature. Furthermore, it appears that the maximum OH concentration for each flame increased with increasing flame temperature.
Book Synopsis Strategies for Planar Laser-induced Fluorescence Thermometry in Shock Tube Flows by : Ji Hyung Yoo
Download or read book Strategies for Planar Laser-induced Fluorescence Thermometry in Shock Tube Flows written by Ji Hyung Yoo and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis was motivated by the need to better understand the temperature distribution in shock tube flows, especially in the near-wall flow regions. Two main ideas in planar laser-induced fluorescence (PLIF) diagnostics are explored in this thesis. The first topic is the development of a single-shot PLIF diagnostic technique for quantitative temperature distribution measurement in shock tube flow fields. PLIF is a non-intrusive, laser-based diagnostic technique capable of instantaneously imaging key flow features, such as temperature, pressure, density, and species concentration, by measuring fluorescence signal intensity from laser-excited tracer species. This study performed a comprehensive comparison of florescence tracers and excitation wavelengths to determine the optimal combination for PLIF imaging in shock tube flow applications. Excitation of toluene at 248nm wavelength was determined to be the optimal strategy due to the resulting high temperature sensitivity and fluorescence signal level, compared to other ketone and aromatic tracers at other excitation wavelengths. Sub-atmospheric toluene fluorescence yield data was measured to augment the existing photophysical data necessary for this diagnostic technique. In addition, a new imaging test section was built to allow PLIF imaging in all regions of the shock tube test section, including immediately adjacent to the side and end walls. The signal-to-noise (SNR) and spatial resolution of the PLIF images were optimized using statistical analysis. Temperature field measurements were made with the PLIF diagnostic technique across normal incident and reflected shocks in the shock tube core flow. The resulting images show uniform spatial distribution, and good agreement with conditions calculated from the normal shock jump equations. Temperature measurement uncertainty is about 3.6% at 800K. The diagnostic was also applied to image flow over a wedge. The resulting images capture all the flow features predicted by numerical simulations. The second topic is the development of a quantitative near-wall diagnostic using tracer-based PLIF imaging. Side wall thermal boundary layers and end wall thermal layers are imaged to study the temperature distribution present under constant pressure conditions. The diagnostic technique validated in the shock tube core flow region was further optimized to improve near-wall image quality. The optimization process considered various wall materials, laser sheet orientations, camera collection angles, and optical components to find the configuration that provides the best images. The resulting images have increased resolution (15[Mu]m) and are able to resolve very thin non-uniform near-wall temperature layers (down to 60[Mu]m from the surface). The temperature field and thickness measurements of near-wall shock tube flows under various shock conditions and test gases showed good agreement with boundary layer theory. To conclude this thesis, new applications and future improvements to the developed PLIF diagnostic technique are discussed. These suggested refinements can provide an even more robust and versatile PLIF imaging technique capable of measuring a wider range of flow conditions near walls.
Download or read book Journal of Fluids Engineering written by and published by . This book was released on 1998 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Laser Induced Fluorescence Gas Puff Density Measurements by : Matthew Thomas Evans
Download or read book Laser Induced Fluorescence Gas Puff Density Measurements written by Matthew Thomas Evans and published by . This book was released on 2012 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: The double gas puff valve is a device used to inject a supersonic puff of gas to act as a load in z-pinch plasma implosions. The purpose of the annular gas shells is to mimic a cylindrical column along the z-axis in efforts to reduce Rayleigh-Taylor instability. However before integration of the valve into the zpinch pulsed power machine the gas profile needs to be examined. Tuning the density of the gas to fit specific profiles leads to improvement in plasma radiative sources and yields. The axial uniformity of the cylindrical gas column is highly dependent on the nozzle characteristics and shape. Performance is then determined by the density, speed, and symmetry of the gas column. Measurement of the density distribution is performed using a spectroscopic measuring technique called laser-induced fluorescence. LIF is a 1-dimensional imaging technique that maps the concentration of atoms with the aid of a tracer. LIF and the 2-dimensional counterpart planar laser-induced fluorescence (PLIF) examine the gas flow in the r-z plane with sub-millimeter resolution. The tracer molecule fluoresces due to excitation by a laser beam. The fluorescence signal is imaged using a streak camera and a charge-coupled-device (CCD) in combination. The method also allows the study of gas puff reliability. Any differences between gas shells can then be examined and interpreted with reliable certainty. Imaging software is used to determine the density from the intensity of the fluorescence images. A detail account of the process is illustrated in this study. A control system was constructed for operations of the gas puff valve in both LIF and z-pinch experiments. The pressure system is designed to tailor specific profiles as needed. The LIF system is detailed along with any components built for the gas puff valve. Results of these measurements serve to verify the uniformity of flow and determine the density distribution of the gas puff.
Book Synopsis Optical Measurements of Fluctuating Temperatures in a Supersonic Turbulent Flow Using One- and Two-photon, Laser-induced Fluorescence by :
Download or read book Optical Measurements of Fluctuating Temperatures in a Supersonic Turbulent Flow Using One- and Two-photon, Laser-induced Fluorescence written by and published by . This book was released on 1984 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
