Download or read book Combined Planar Measurements of Velocity and Pressure Fields in Compressible Gas Flows Using Laser induced Iodine Fluorescence written by Bernhard Hiller and published by . This book was released on 1986 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Tracer based Planar Laser induced Fluorescence Diagnostics written by Brian Ho-yin Cheung and published by Stanford University. This book was released on 2011 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two advances to tracer-based planar laser-induced fluorescence (PLIF) diagnostics are presented in this work. The first improvement is the development of a 3-pentanone fluorescence quantum yield (FQY) database and model for a wide range of conditions in support of quantitative PLIF diagnostics. In addition, this work presents a sensitive, time-resolved tracer-based PLIF diagnostic, accomplished by using a continuous-wave (CW) laser with the high-FQY tracer toluene. Because of its ease of use and desirable photophysical properties, PLIF diagnostics using 3-pentanone as a tracer are common, particularly for internal combustion engine (ICE) diagnostics. Thus, there is a need for 3-pentanone FQY measurements and modeling over a wide range of temperatures, pressures, and excitation wavelengths. For insight into the collisionless process in the FQY model, measurements were made in 3-pentanone vapor at low-pressures across a range of temperatures using a flowing cell. Laser excitation with 248, 266, 277, 308 nm wavelengths were utilized, and Rayleigh scattering of the laser beam was used to calibrate the optical efficiency of the collection optics and detector. This low-pressure data allows calculation of the 3-pentanone fluorescence rate and non-radiative de-excitation rate in the fluorescence model. The vibrational relaxation cascade parameter for 3-pentanone collisions was also determined. Measurements of 3-pentanone FQY were also made over a range of temperatures and pressures relevant to diagnostic applications, and, in particular, combined high-temperature and high-pressure conditions applicable to internal combustion engines (ICE). These data were collected in a custom-built optical cell capable of simultaneous high-pressure and high-temperature conditions. The behavior of the FQY in nitrogen for temperatures up to 745 K and in air up to 570 K was examined for pressures from 1 to 25 bar. These data were used to further optimize the parameters in the FQY model representing collisional processes. The large quantity of data with 308 nm excitation allowed optimization of the nitrogen quenching rate, and data in air were used to optimize the oxygen quenching rate. These data were also used to optimize the vibrational relaxation parameters for nitrogen and oxygen. The model with the updated parameters is consistent with the data collected in the current work, as well as with fluorescence measurements made in optical ICEs up to 1100 K and 28 bar. Another area of tracer-based PLIF diagnostics development is time-resolved imaging. Because PLIF diagnostics are often performed using pulsed lasers, the time resolution of measurements is limited to the pulse rate of laser. Use of a high-powered visible laser with an off-the-shelf cavity frequency doubler is shown to produce a moderate-power CW beam in the ultraviolet wavelength regime. Application of this CW source to excite toluene, a high-FQY tracer, yields a sensitive, time-resolved tracer-based PLIF diagnostic. Fluctuation detection limits for tracer mole fraction were investigated by applying the diagnostic to an atmospheric temperature and pressure nitrogen jet seeded with 4% toluene, and detection limits of better than 1% of the maximum toluene mole fraction were achieved for detection of fluorescence signal at a point, along a line, and over a plane. The diagnostic was also demonstrated on a turbulent jet for line and planar detection and demonstrated the potential for toluene time-resolved PLIF diagnostics with CW lasers.
Download or read book Proceedings of the ASME Fluids Engineering Division Summer Meeting written by American Society of Mechanical Engineers. Fluids Engineering Division. Summer Meeting and published by . This book was released on 1996 with total page 680 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AIAA 90 1835 AIAA 90 1881 written by and published by . This book was released on 1990 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Flow Visualization written by and published by . This book was released on 1995 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Previews of Heat and Mass Transfer written by and published by . This book was released on 1987 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Laser Induced Fluorescence Modulation Techniques for Velocity Measurements in Gas Flows written by C. Hassa and published by . This book was released on 1987 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Broadband fluorescence of iodine, excited at 514.5 nm by a single-mode argon-ion laser tuned to the quasi-linear part of an absorption line, was used to detect the Doppler shift and hence the velocity of iodine molecules seeded in a nitrogen jet flow. The slope of the absorption line profile was measured directly using a frequency shift introduced by acoustooptic modulators (AOMs). A velocity of 36 m/s was measured in a jet of N2 at 60 Torr in 2 ms with an accuracy of 11%. To reduce experimental noise, the laser beams were switched at 125 KHz and signal-tuned amplification was used. Keywords: velocity, Iodine, Laser, Fluorescence.
Download or read book Velocity Measurements in High Temperature Gases Using Laser Induced No Fluorescence written by and published by . This book was released on 1991 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the results of a Phase I SBIR program which investigated the applicability of a Laser Induced Fluorescence (LIF) velocimetry diagnostic technique based on Doppler-shifted NO fluorescence. The intent of the program was to quantitatively understand the potential accuracy of the approach in high-temperature, high-pressure gas flow applications when one is restricted to use only a single laser wavelength. The single laser wavelength approach greatly simplifies the experimental requirements while retaining the capability of simultaneous, multiple-point velocity field measurements. The report summarizes detailed analytical studies which demonstrate that, for representative NO lineshapes and available pulse dye lasers, single-shot measurements of the instantaneous velocity field are possible in essentially uncharacterized pressure and temperature fields with less than 10 percent uncertainty. When a priori information on the pressure or temperature field is available, the instantaneous measurement uncertainty is reduced to less than 5 percent.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1989 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Numerical Flow Visualization 1995 written by and published by . This book was released on 1995 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Optics and Lasers in Engineering written by Gabriel Laufer and published by Cambridge University Press. This book was released on 1996-07-13 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a very short time, lasers advanced from research interest to increasingly useful, commercially available tools for material processing, precision measurements, surgery, communication, and even entertainment. This 1996 book provides the background in theoretical physics necessary to understand engineering applications. It summarises relevant theories of geometrical optics, physical optics, quantum optics, and laser physics and ties them to applications in such areas as fluid mechanics, combustion, surface analysis, material processing and laser machining. Advanced topics such as laser Doppler velocimetry, laser-induced fluorescence, and holography are clearly and thoroughly explained. The book includes numerous examples and homework problems. A unique feature is the advanced research problems in each chapter that simulate real-world research and encourage independent reading and analysis.
Download or read book 34th AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit written by and published by . This book was released on 1998 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1996 with total page 1012 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paper written by and published by . This book was released on 1996 with total page 524 pages. Available in PDF, EPUB and Kindle. Book excerpt:
