Download or read book Velocity Field Measurements in Rarefied Hypersonic Flows of Nitrogen Using Laser induced Fluorescence of Iodine written by Eric Cecil and published by . This book was released on 2011 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Iodine Tagging Velocimetry and Mechanism in the Hypersonic Near Wake of a Multipurpose Crew Vehicle written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019-01-13 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study demonstrates a new molecular tagging velocimetry (MTV) method for velocity measurements of high speed flow. It demonstrates offbody Iodine Tagging Velocimetry (ITV) in the hypersonic near wake of a MultiPurpose Crew Vehicle (MPCV) model. Experiments are performed in the NASA-Langley 31-inch Mach 10 air wind tunnel. A 0.5% I2 / N2 mixture is seeded on the leeward backshell of the model using a pressure tap. I2 laser-induced fluorescence is excited along a 5.5 mm line using an ArF excimer laser near 193 nm. Results indicate I2 absorbs at least 2 photons to produce iodine ions and electrons. These recombine as the tagged region is displaced downstream to produce I (2P3/2) whose emission is monitored at 206 nm. Results at P0 = 2.41 MPa (350 psi), T0 = 990K, and 10 micro-sec transit times produce velocities from 630-820 m/sec across the I2 seeded jet at a distance of 38.2 mm (25.5 jet diameters) downstream from the jet orifice. Maximum wake jet velocities near the shear layer are 59% of freestream velocity. Balla, R. Jeffrey Langley Research Center WBS 478076.07.27.07
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 Laser spectroscopic Measurement Techniques for Hypersonic Turbulent Wind Tunnel Flows written by and published by . This book was released on 1992 with total page 18 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 International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 1032 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Laser Spectroscopic Measurement Techniques for Hypersonic Turbulent Wind Tunnel Flows written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-12-29 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A review is given of the nature, present status, and capabilities of two laser spectroscopic methods for the simultaneous measurement of temperature, density, and their fluctuations owing to turbulence in high speed wind tunnel flows. One method is based on the two frequency excitation of nitric oxide seeded into a nitrogen flow, using tunable dye lasers. The second, more recent method relies on the excitation of oxygen in air flows using a tunable, ArF excimer laser. Signal are obtained from both the laser induced fluorescence and from Raman scattering of the same laser pulse. Measurements are demonstrated in the turbulent boundary layer of a Mach-2 channel flow. Mckenzie, Robert L. and Fletcher, Douglas G. Ames Research Center NASA-TM-103928, A-92076, NAS 1.15:103928 RTOP 505-59-40...
Download or read book On the measurement of flow field properties near the optical window of a hypersonic interceptor by means of laser induced fluorescence spectroscopy written by Kandasamy Vaidyalingam and published by . This book was released on 1995 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Drift Wave Ion Fluid Velocity Field Measured by Planar Laser Induced Fluorescence written by Andrew Dewey Bailey and published by . This book was released on 1993 with total page 324 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Two Dimensional Imaging Measurements in Supersonic Flows Using Laser Induced Fluorescence of Oxygen written by L. M. Cohen and published by . This book was released on 1987 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Planar laser induced fluorescence of molecular oxygen in a supersonic jet of heated air is reported. A tunable, narrow-bandwidth ArF excimer laser was used to excite a rovibronic transition of oxygen in the Schumann-Runge band system at 193 nm. A comparison between the predicted pressure and temperature profiles obtained in the underexpanded round jet with the fluorescence image data is presented. Keywords: Laser, Fluorescence, Imaging, Oxygen, Supersonic Flow, Excimer.
Download or read book Investigation of Low pressure Laser Induced Fluorescence for Measuring Temperature Profiles in a Rarefied Gas written by Thomas Orville Leimkuehler and published by . This book was released on 2000 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a rarefied gas, heat transfer in the transition regime (i.e., Knudsen number range of 0.1 to 10) is affected by molecular as well as gas-surface interactions. Theoretical results for the heat transfer can be obtained through computational solutions of the Boltzmann equation and appropriate intermolecular and gas-surface interaction models. As with all computational and phenomenological models, experimental verification is required. In this work, a low-pressure laser induced fluorescence (LIF) technique is investigated for measuring temperature profiles between parallel flat plates, and the results are compared to theoretical predictions. Iodine vapor is used as the gas medium due to its attractive spectral properties. Two surfaces of a closed, short cylindrical iodine cell are employed as a parallel flat plate geometry and are maintained at different temperatures. Cold and hot plate temperature combinations of (1) 20°C and 70°C, respectively, and (2) 20°C and 115°C, respectively, were used. Calibration measurements were performed at uniform temperatures of 45°C and 70°C, Solid iodine stem temperatures of 0°C and -20°C, corresponding to pressures of 30 mtorr and 3 mtorr, respectively, and Knudsen numbers of 0.05 and 0.5, respectively, were investigated. The data shows the expected trends, indicating observable temperature jumps at the surfaces and matching well with the theoretical predictions in the bulk gas. Deviations from the theory were largest near the surface, possibly a result of the limitations of the theoretical models for this particular experimental case. In addition, problems stemming from fluctuations of the chamber pressure as well as attenuation of the excitation laser beam affected collection of definitive temperature profile measurements. However, much progress with the low-pressure LIF technique has been made, and the technique continues to look promising for obtaining accurate and reliable temperature profile measurements in the transition regime.
Download or read book Laser induced Fluorescence Modulation Technique for Velocity Measurements in Gas Flows written by Christoph Johannes Hassa and published by . This book was released on 1985 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book NASA SP written by and published by . This book was released on 1993 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental Study of Interacting Rarefied and Continuum Flows Using Planar Laser induced Iodine Fluorescence written by David A. Staack and published by . This book was released on 2001 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Temperature measurements in hypersonic air flows using laser induced O2 fluorescence written by Gabriel Laufer and published by . This book was released on 1988 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1996 with total page 724 pages. Available in PDF, EPUB and Kindle. Book excerpt:
