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Shekhtman D, Yu WM, Mustafa MA, Parziale NJ, Austin JM. Freestream velocity-profile measurement in a large-scale, high-enthalpy reflected-shock tunnel. EXPERIMENTS IN FLUIDS 2021; 62:118. [PMID: 33967381 PMCID: PMC8097679 DOI: 10.1007/s00348-021-03207-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 04/08/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
ABSTRACT We apply Krypton Tagging Velocimetry (KTV) to measure velocity profiles in the freestream of a large, national-scale high-enthalpy facility, the T5 Reflected-Shock Tunnel at Caltech. The KTV scheme utilizes two-photon excitation at 216.67 nm with a pulsed dye laser, followed by re-excitation at 769.45 nm with a continuous laser diode. Results from a nine-shot experimental campaign are presented where N 2 and air gas mixtures are doped with krypton, denoted as 99% N 2 /1% Kr, and 75% N 2 /20% O 2 /5% Kr, respectively. Flow conditions were varied through much of the T5 parameter space (reservoir enthalpy h R ≈ 5 - 16 MJ/kg). We compare our experimental freestream velocity-profile measurements to reacting, Navier-Stokes nozzle calculations with success, to within the uncertainty of the experiment. Then, we discuss some of the limitations of the present measurement technique, including quenching effects and flow luminosity; and, we present an uncertainty estimate in the freestream velocity computations that arise from the experimentally derived inputs to the code.
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Affiliation(s)
- D. Shekhtman
- Stevens Institute of Technology, Hoboken, NJ 07030 USA
| | - W. M. Yu
- California Institute of Technology, Pasadena, CA 91125 USA
| | - M. A. Mustafa
- Stevens Institute of Technology, Hoboken, NJ 07030 USA
| | | | - J. M. Austin
- California Institute of Technology, Pasadena, CA 91125 USA
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Fisher JM, Brown AD, Lauriola DK, Slipchenko MN, Meyer TR. Femtosecond laser activation and sensing of hydroxyl for velocimetry in reacting flows. APPLIED OPTICS 2020; 59:10853-10861. [PMID: 33361906 DOI: 10.1364/ao.404788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 11/03/2020] [Indexed: 06/12/2023]
Abstract
A molecular tagging method for velocity measurements in reacting environments such as propulsion devices and high-temperature combustion-assisted wind tunnels is described. The method employs a femtosecond (write) laser to photodissociate H2O, a common combustion product, into a locally high concentration of OH radicals. These radicals are tracked by planar laser-induced fluorescence (PLIF) from the A2Σ-X2Π (1-0) vibrational band excited by a time-delayed 284 nm (read) laser sheet. As a variant of hydroxyl tagging velocimetry, the source laser can also be used to dissociate nitrogen for femtosecond laser electronic excitation tagging velocimetry to mark the time-zero location of the write laser for velocimetry in non-reacting regions using the same imaging system without OH PLIF. The OH tracer lifetime is studied in a hydrogen-air Hencken burner operating at Φ=0.5-1.8 to evaluate the tracking capability for velocimetry over a range of conditions. Effects of changing read laser wavelength, excitation energy, and influence of background flame emission are also studied. The data processing methodology and results are described for tracking displacements with 9-25 µm uncertainty in a hydrogen diffusion flame. This method presents several advantages in operational convenience and availability of laser sources, and it provides an avenue for improvements in the repetition rate, precision, and applicability over previously demonstrated hydroxyl tagging schemes.
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Hada M, Shigeeda Y, Koshihara SY, Nishikawa T, Yamashita Y, Hayashi Y. Bond Dissociation Triggering Molecular Disorder in Amorphous H 2O. J Phys Chem A 2018; 122:9579-9584. [PMID: 30430832 DOI: 10.1021/acs.jpca.8b08455] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We developed a system to deposit H2O molecules onto ultrathin silicon nitride substrates in situ using time-resolved transmission electron diffraction apparatus and performed ultrafast time-resolved electron diffraction measurements in the noncrystalline (amorphous) H2O under near-ultraviolet photoexcitation. The observed dynamics directly represent O-H bond dissociation via multiphoton absorption and charge transfer, which trigger ionization and intermolecular disorder in the amorphous H2O. Our results illustrate the intriguing nature of light-matter and matter-matter interactions in H2O molecules.
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Affiliation(s)
- Masaki Hada
- Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Yuho Shigeeda
- Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Shin-Ya Koshihara
- School of Science , Tokyo Institute of Technology , Tokyo 152-8551 , Japan
| | - Takeshi Nishikawa
- Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Yoshifumi Yamashita
- Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
| | - Yasuhiko Hayashi
- Graduate School of Natural Science and Technology , Okayama University , Okayama 700-8530 , Japan
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Zhang D, Li B, Gao Q, Li Z. Applicability of Femtosecond Laser Electronic Excitation Tagging in Combustion Flow Field Velocity Measurements. APPLIED SPECTROSCOPY 2018; 72:1807-1813. [PMID: 29972316 DOI: 10.1177/0003702818788857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Femtosecond laser electronic excitation tagging (FLEET) is a molecular tagging velocimetry technique that can be applied in combustion flow fields, although detailed studies of its application in combustion are still needed. We report the applicability of FLEET in premixed CH4-air flames. We found that FLEET can be applied in all of the combustion areas (e.g., the unburned region, the burned region and the reaction zone). The FLEET signal in the unburned region is significantly higher than that in the burned region. This technique is suitable for both lean and rich CH4-air combustion flow fields and its performance in lean flames is better than that in rich flames.
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Affiliation(s)
- Dayuan Zhang
- State Key Laboratory of Engines, Tianjin University, China
| | - Bo Li
- State Key Laboratory of Engines, Tianjin University, China
| | - Qiang Gao
- State Key Laboratory of Engines, Tianjin University, China
| | - Zhongshan Li
- State Key Laboratory of Engines, Tianjin University, China
- Division of Combustion Physics, Lund University, Sweden
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Parziale NJ, Smith MS, Marineau EC. Krypton tagging velocimetry of an underexpanded jet. APPLIED OPTICS 2015; 54:5094-101. [PMID: 26192670 DOI: 10.1364/ao.54.005094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
In this work, we present the excitation/emission strategy, experimental setup, and results of an implementation of krypton tagging velocimetry (KTV). KTV is performed as follows: (i) seed a base flow with krypton; (ii) photosynthesize metastable krypton atoms with a frequency-doubled dye laser to form the tagged tracer; (iii) record the translation of the tagged metastable krypton by imaging the laser-induced fluorescence (LIF) that is produced with an additional dye laser. The principle strength of KTV, relative to other tagging velocimetry techniques, is the use of a chemically inert tracer. KTV results are presented for an underexpanded jet of three mixtures of varying Kr/N2 concentration. It is demonstrated that KTV can be used in gas mixtures of relatively low krypton mole fraction (0.5% Kr/99.5% N2), and the KTV data from that experiment are found to be in good agreement with an empirical fit found in the literature. We find that KTV is useful to perform instantaneous velocity measurements with metastable krypton as a chemically inert, dilute, long-lifetime tracer in gas-phase flows.
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Grady N, Pitz RW. Vibrationally excited hydroxyl tagging velocimetry. APPLIED OPTICS 2014; 53:7182-7188. [PMID: 25402874 DOI: 10.1364/ao.53.007182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A new molecular-based velocity method is developed for high-temperature flame gases based on the hydroxyl tagging velocimetry (HTV) technique. In vibrationally excited HTV (VE-HTV), two photons from a KrF laser (248 nm) dissociate H2O into a tag line of vibrationally excited OH (v=1). The excited state OH tag is selectively detected in a background of naturally occurring ground state OH (v=0). In atmospheric pressure laboratory burners, the OH (v=1) tag persists for 5-10 μs, allowing single-shot velocity measurements along a 2 cm line under lean, stoichiometric, and rich flame conditions with temperatures reaching 2300 K. Mean velocity measurements are demonstrated in a lean (ϕ=0.78) premixed H2/air turbulent flame (Re=26,550) laboratory flame. The VE-HTV method is best suited to measure high-speed velocities in hot combustion environments in the presence of background OH.
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Michael JB, Edwards MR, Dogariu A, Miles RB. Femtosecond laser electronic excitation tagging for quantitative velocity imaging in air. APPLIED OPTICS 2011; 50:5158-62. [PMID: 21946998 DOI: 10.1364/ao.50.005158] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Time-accurate velocity measurements in unseeded air are made by tagging nitrogen with a femtosecond-duration laser pulse and monitoring the displacement of the molecules with a time-delayed, fast-gated camera. Centimeter-long lines are written through the focal region of a ∼1 mJ, 810 nm laser and are produced by nonlinear excitation and dissociation of nitrogen. Negligible heating is associated with this interaction. The emission arises from recombining nitrogen atoms and lasts for tens of microseconds in natural air. It falls into the 560 to 660 nm spectral region and consists of multiple spectral lines associated with first positive nitrogen transitions. The feasibility of this concept is demonstrated with lines written across a free jet, yielding instantaneous and averaged velocity profiles. The use of high-intensity femtosecond pulses for flow tagging allows the accurate determination of velocity profiles with a single laser system and camera.
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Affiliation(s)
- James B Michael
- Mechanical and Aerospace Engineering, Princeton University, Engineering Quadrangle, Princeton, New Jersey 08540, USA
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Hsu AG, Srinivasan R, Bowersox RDW, North SW. Two-component molecular tagging velocimetry utilizing NO fluorescence lifetime and NO2 photodissociation techniques in an underexpanded jet flowfield. APPLIED OPTICS 2009; 48:4414-4423. [PMID: 19649046 DOI: 10.1364/ao.48.004414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report the application of molecular tagging velocimetry (MTV) toward two-component velocimetry as demonstrated in an underexpanded free jet flowfield. Two variants of the MTV technique are presented: 1) electronic excitation of seeded nitric oxide (NO) with gated fluorescence imaging (fluorescence lifetime) and 2) photodissociation of seeded NO2 followed by NO fluorescence imaging (NO2 photodissociation). The seeded NO fluorescence lifetime technique is advantageous in low-quenching, high-velocity flowfields, while the photodissociation technique is useful in high-quenching environments, and either high- or low-velocity flowfields due to long lifetime of the NO photoproduct. Both techniques are viable for single-shot measurements, with determined root mean squared results for streamwise and radial velocities of approximately 5%. This study represents the first known application of MTV utilizing either the fluorescence lifetime or the photodissociation technique toward two-component velocity mapping in a gaseous flowfield. Methods for increasing the spatial resolution to be comparable to particle-based tracking techniques are discussed.
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Affiliation(s)
- Andrea G Hsu
- Department of Chemistry, Texas A&M University, 3012 TAMU, College Station, Texas 77842, USA
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Bominaar J, Pashtrapanska M, Elenbaas T, Dam N, ter Meulen H, van de Water W. Writing in turbulent air. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:046312. [PMID: 18517737 DOI: 10.1103/physreve.77.046312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2007] [Indexed: 05/26/2023]
Abstract
We describe a scheme of molecular tagging velocimetry in air in which nitric oxide (NO) molecules are created out of O2 and N2 molecules in the focus of a strong laser beam. The NO molecules are visualized a while later by laser-induced fluorescence. The precision of the molecular tagging velocimetry of gas flows is affected by the gradual blurring of the written patterns through molecular diffusion. In the case of turbulent flows, molecular diffusion poses a fundamental limit on the resolution of the smallest scales in the flow. We study the diffusion of written patterns in detail for our tagging scheme which, at short (micros) delay times is slightly anomalous due to local heating by absorption of laser radiation. We show that our experiments agree with a simple convection-diffusion model that allows us to estimate the temperature rise upon writing. Molecular tagging can be a highly nonlinear process, which affects the art of writing. We find that our tagging scheme is (only) quadratic in the intensity of the writing laser.
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Affiliation(s)
- Jeroen Bominaar
- Institute of Molecules and Materials, Applied Molecular Physics, Radboud University, Nijmegen, The Netherlands
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Choi JH, Lucas D, Koshland CP, Sawyer RF. Photochemical Interaction of Polystyrene Nanospheres with 193 nm Pulsed Laser Light. J Phys Chem B 2005; 109:23905-10. [PMID: 16375376 DOI: 10.1021/jp0540611] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The photochemical interaction of 193 nm light with polystyrene nanospheres is used to produce particles with a controlled size and morphology. Laser fluences from 0 to 0.14 J/cm2 at 10 and 50 Hz photofragment nearly monodisperse 110 nm spherical polystyrene particles. The size distributions before and after irradiation are measured with a scanning mobility particle sizer (SMPS), and the morphology of the irradiated particles is examined with a transmission electron microscope (TEM). The results show that the irradiated particles have a smaller mean diameter ( approximately 25 nm) and a number concentration more than an order of magnitude higher than nonirradiated particles. The particles are formed by nucleation of gas-phase species produced by photolytic decomposition of nanospheres. A nondimensional parameter, the photon-to-atom ratio (PAR), is used to interpret the laser-particle interaction energetics.
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Affiliation(s)
- Jong Hyun Choi
- Mechanical Engineering Department, University of California, Berkeley, California 94720, USA.
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Pitz RW, Lahr MD, Douglas ZW, Wehrmeyer JA, Hu S, Carter CD, Hsu KY, Lum C, Koochesfahani MM. Hydroxyl tagging velocimetry in a supersonic flow over a cavity. APPLIED OPTICS 2005; 44:6692-700. [PMID: 16270558 DOI: 10.1364/ao.44.006692] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Hydroxyl tagging velocimetry (HTV) measurements of velocity were made in a Mach 2 (M 2) flow with a wall cavity. In the HTV method, ArF excimer laser (193 nm) beams pass through a humid gas and dissociate H2O into H + OH to form a tagging grid of OH molecules. In this study, a 7 x 7 grid of hydroxyl (OH) molecules is tracked by planar laser-induced fluorescence. The grid motion over a fixed time delay yields about 50 velocity vectors of the two-dimensional flow in the plane of the laser sheets. Velocity precision is limited by the error in finding the crossing location of the OH lines written by the excimer tag laser. With a signal-to-noise ratio of about 10 for the OH lines, the determination of the crossing location is expected to be accurate within +/- 0.1 pixels. Velocity precision within the freestream, where the turbulence is low, is consistent with this error. Instantaneous, single-shot measurements of two-dimensional flow patterns were made in the nonreacting M 2 flow with a wall cavity under low- and high-pressure conditions. The single-shot profiles were analyzed to yield mean and rms velocity profiles in the M 2 nonreacting flow.
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Affiliation(s)
- Robert W Pitz
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
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Ribarov LA, Hu S, Wehrmeyer JA, Pitz RW. Hydroxyl tagging velocimetry method optimization: signal intensity and spectroscopy. APPLIED OPTICS 2005; 44:6616-26. [PMID: 16270550 DOI: 10.1364/ao.44.006616] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
The previously demonstrated nonintrusive time-of-flight molecular velocity tagging method, hydroxyl tagging velocimetry (HTV), has shown the capability of operating both at room temperature and in flames. Well-characterized jets of either air (nonreacting cases) or hydrogen-air diffusion flames (reacting cases) are employed. A 7 x 7 OH line grid is generated first through the single-photon photodissociation of H2O by a approximately 193 nm pulsed narrowband ArF excimer laser and is subsequently revealed by a read laser sheet through fluorescence caused by A2sigma+(v' = 3) <-- X2pi(i)(v'' = 0), A2sigma+(v' = 1) <-- X2pi(i)(v'' = 0), or A2sigma+(v' = 0) < or = X2pi(i)(v'' = 0) pumping at approximately 248, approximately 282, or approximately 308 nm, respectively. A detailed discussion of the spectroscopy and relative signal intensity of these various read techniques is presented, and the implications for optimal HTV performance are discussed.
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Affiliation(s)
- Lubomir A Ribarov
- Department of Mechanical Engineering, Vanderbilt University, Nashville, Tennessee 37235, USA.
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van Harrevelt R, van Hemert MC. Photodissociation of water in the à band revisited with new potential energy surfaces. J Chem Phys 2001. [DOI: 10.1063/1.1370946] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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