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Satija A, Lucht RP. Simultaneous Temperature and Pressure Measurements in Compressible Flow Using Nanosecond O 2 Coherent Anti-Stokes Raman Spectroscopy. APPLIED SPECTROSCOPY 2022; 76:541-547. [PMID: 35209722 DOI: 10.1177/00037028221081520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Simultaneous pure-rotational coherent anti-Stokes Raman spectroscopy (PRCARS) and vibrational O2 CARS spectroscopy (VCARS) were performed at elevated pressure and lowered temperature conditions in non-reacting compressible flow. We applied dual-pump CARS in a three-laser, three-color configuration to simultaneously acquire the PRCARS and VCARS spectra of O2. PRCARS spectra provide excellent sensitivity to temperature at relatively low temperatures. Pressure was extracted using the differential response of collisional effects in the PRCARS and the VCARS spectra. We used an under-expanded jet outside a choked converging nozzle as the compressible flow-field. We numerically analyze the pressure sensitivity of the combined CARS technique. Finally, we compare the collisional narrowing lineshape models of rotational diffusion narrowing and modified-exponential-gap model, for fitting the experimental spectrum.
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Affiliation(s)
- Aman Satija
- School of Mechanical Engineering, 8522Purdue University, West Lafayette, IN, USA
| | - Robert P Lucht
- School of Mechanical Engineering, 8522Purdue University, West Lafayette, IN, USA
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Smyser ME, Braun EL, Athmanathan V, Slipchenko MN, Roy S, Meyer TR. Dual-output fs/ps burst-mode laser for megahertz-rate rotational coherent anti-Stokes Raman scattering. OPTICS LETTERS 2020; 45:5933-5936. [PMID: 33137036 DOI: 10.1364/ol.404984] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 09/25/2020] [Indexed: 06/11/2023]
Abstract
A burst-mode laser system is developed for hybrid femtosecond/picosecond (fs/ps) rotational coherent anti-Stokes Raman scattering (RCARS) at megahertz rates. Using a common fs oscillator, the system simultaneously generates time synchronized 1061 nm, 274 fs and 1064 nm, 15.5 ps pulses with peak powers of 350 MW and 2.5 MW, respectively. The system is demonstrated for two-beam fs/ps RCARS in N2 at 1 MHz with a signal-to-noise ratio of 176 at room temperature. This repetition rate is an order of magnitude higher than previous CARS using burst-mode ps laser systems and two to three orders of magnitude faster than previous continuously pulsed fs or fs/ps laser systems.
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Rock N, Hsu PS, Lauriola D, Rahman N, Estevadeordal J, Grib SW, Jiang N, Kearney SP, Wrzesinski P. WIDECARS multi-parameter measurements in premixed ethylene-air flames using a wavelength stable ultrabroadband dye laser. APPLIED OPTICS 2020; 59:2649-2655. [PMID: 32225810 DOI: 10.1364/ao.386378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 02/16/2020] [Indexed: 06/10/2023]
Abstract
Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) measurements were used to determine the temperature and major species mole fractions in laminar, premixed, ethylene-air flames operating at atmospheric pressure. Conventional ultrabroadband dye lasers for WIDECARS, which use Pyrromethene dyes, have historically suffered from day-to-day wavelength shifting. To overcome this problem, a new ultrabroadband dye laser was developed in this study to provide a stable wavelength and power generation. A new dye laser pumping scheme and a mixture of Sulforhodamine 640, Kiton Red 620, and Rhodamine 640, was used to generate the desired FWHM ${\sim}{15}\;{\rm nm}$∼15nm (${410}\;{{\rm cm}^{ - 1}}$410cm-1) bandwidth. The WIDECARS measured mole fraction ratios of ${{\rm CO}_2}$CO2, CO, and ${{\rm H}_2}$H2 with ${{\rm N}_2}$N2 agreed well with chemical equilibrium calculations.
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Krishna Y, Elbaz AM, Yue Y, Magnotti G. Mole fraction measurement through a transparent quarl burner using filtered Rayleigh scattering. APPLIED OPTICS 2019; 58:5575-5586. [PMID: 31504030 DOI: 10.1364/ao.58.005575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/16/2019] [Indexed: 06/10/2023]
Abstract
A filtered Rayleigh scattering system is developed and applied to measure the mole fraction of methane in a methane-air swirl flow through a transparent conical quartz quarl. Light scattering from the location where the laser beam is incident on the surface of the quarl is orders of magnitudes larger than Rayleigh scattering from the gas mixture of interest. This diffusive scattering is suppressed using molecular absorption by an iodine cell and using spatial filtering by an optical aperture. Residual stray light accounted for up to 5% of the total signal and had to be removed for accurate measurements. The flow consisted of a nonpremixed mixture of methane and air in the central jet surrounded by a strong swirling air flow. Measurements were conducted at a height of 4 mm from the fuel tube's exit for six different conditions of the swirl flow to demonstrate the ability of the instrument to study the effects of swirl strength and fuel flow rate on the mixing process. By using a four-leg pulse stretcher to allow higher laser energies in the probe volume, large collection optics and a reference iodine cell to monitor laser wavelength variations, standard deviations of ∼0.006 in air and ∼0.012 in a laminar methane flow were achieved for mole fraction measurements.
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Cutler AD, Gallo ECA, Cantu LML. Coherent anti-Stokes Raman spectroscopy measurement of ethylene in combustion. APPLIED OPTICS 2017; 56:E30-E36. [PMID: 28414339 DOI: 10.1364/ao.56.000e30] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Width-increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) has been developed for spatially and temporally resolved simultaneous measurement of temperature and mole fraction of most major species in ethylene-air flames. This paper describes a method to infer coherent anti-Stokes Raman spectroscopy complex susceptibility distributions of the ν3 band of ethylene from WIDECARS spectra measured in heated mixtures of ethylene and air, and to use such distributions to fit experimental WIDECARS spectra in an ethylene-air flame. The method is used to measure mole fraction ethylene in a dual-mode supersonic combustor burning premixed ethylene and air with single-laser-shot precision (one standard deviation) of ±0.0025 (absolute).
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Ehn A, Zhu J, Li X, Kiefer J. Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering. APPLIED SPECTROSCOPY 2017; 71:341-366. [PMID: 28155328 DOI: 10.1177/0003702817690161] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.
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Affiliation(s)
- Andreas Ehn
- 1 Combustion Physics, Lund University, Lund, Sweden
| | - Jiajian Zhu
- 2 Science and Technology on Scramjet Laboratory, National University of Defense Technology, Changsha, China
| | - Xuesong Li
- 3 Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Johannes Kiefer
- 4 Technische Thermodynamik and MAPEX Center for Materials and Processes, Universität Bremen, Bremen, Germany
- 5 School of Engineering, University of Aberdeen, Aberdeen, UK
- 6 Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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Campbell MF, Bohlin GA, Schrader PE, Bambha RP, Kliewer CJ, Johansson KO, Michelsen HA. Design and characterization of a linear Hencken-type burner. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:115114. [PMID: 27910522 DOI: 10.1063/1.4967491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We have designed and constructed a Hencken-type burner that produces a 38-mm-long linear laminar partially premixed co-flow diffusion flame. This burner was designed to produce a linear flame for studies of soot chemistry, combining the benefit of the conventional Hencken burner's laminar flames with the advantage of the slot burner's geometry for optical measurements requiring a long interaction distance. It is suitable for measurements using optical imaging diagnostics, line-of-sight optical techniques, or off-axis optical-scattering methods requiring either a long or short path length through the flame. This paper presents details of the design and operation of this new burner. We also provide characterization information for flames produced by this burner, including relative flow-field velocities obtained using hot-wire anemometry, temperatures along the centerline extracted using direct one-dimensional coherent Raman imaging, soot volume fractions along the centerline obtained using laser-induced incandescence and laser extinction, and transmission electron microscopy images of soot thermophoretically sampled from the flame.
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Affiliation(s)
- M F Campbell
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - G A Bohlin
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - P E Schrader
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - R P Bambha
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - C J Kliewer
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - K O Johansson
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
| | - H A Michelsen
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94550, USA
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Bohlin A, Kliewer CJ. Diagnostic Imaging in Flames with Instantaneous Planar Coherent Raman Spectroscopy. J Phys Chem Lett 2014; 5:1243-1248. [PMID: 26274479 DOI: 10.1021/jz500384y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Spatial mapping of temperature and molecular species concentrations is vitally important in studies of gaseous chemically reacting flows. Temperature marks the evolution of heat release and energy transfer, while species concentration gradients provide critical information on mixing and chemical reaction. Coherent anti-Stokes Raman spectroscopy (CARS) was pioneered in measurements of such processes almost 40 years ago and is authoritative in terms of the accuracy and precision it may provide. While a reacting flow is fully characterized in three-dimensional space, a limitation of CARS has been its applicability as a point-wise measurement technique, motivating advancement toward CARS imaging, and attempts have been made considering one-dimensional probing. Here, we report development of two-dimensional CARS, with the first diagnostics of a planar field in a combusting flow within a single laser pulse, resulting in measured isotherms ranging from 450 K up to typical hydrocarbon flame temperatures of about 2000 K with chemical mapping of O2 and N2.
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Affiliation(s)
- A Bohlin
- Sandia National Laboratories, Livermore, California 94551, United States
| | - C J Kliewer
- Sandia National Laboratories, Livermore, California 94551, United States
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