Rotational and vibrational temperature measurements using CARS in a hypervelocity shock layer flow and comparisons with CFD calculations

Boyce, Russell; Pulford, D. R. N.; Houwing, A. F. P.; Mundt, Christian

doi:10.1007/bf02511403

Cited by 18 publications

(9 citation statements)

References 20 publications

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“…Grisch et al [56] used narrowband dualline N 2 CARS in folded BoxCARS geometry to measure 2D distributions of N 2 rotational temperature and number density in Mach 10 nitrogen flow, in a shock wave-boundary layer interaction region behind compression corner. Pulford et al [57] and Boyce et al [58] used single-shot broadband N 2 CARS spectra, also in folded BoxCARS geometry, for measurements of N 2 rotational and vibrational temperatures in a pulsed free piston supersonic shock tunnel flow facility, both in freestream and in a bow shock layer in front of a blunt body. In these experiments, significant vibrational nonequilibrium was detected in freestream, T rot = 850 ± 100 K, T vib(0,1) = 1985 ± 200 K, while the flow in the shock layer was near equilibrium, T rot = 3730 ± 400 K, T vib(0,1) = 4000 ± 200 K [58].…”

Section: Vibrational Cars: Vibrational and Rotational Temperatures Inmentioning

confidence: 99%

“…Pulford et al [57] and Boyce et al [58] used single-shot broadband N 2 CARS spectra, also in folded BoxCARS geometry, for measurements of N 2 rotational and vibrational temperatures in a pulsed free piston supersonic shock tunnel flow facility, both in freestream and in a bow shock layer in front of a blunt body. In these experiments, significant vibrational nonequilibrium was detected in freestream, T rot = 850 ± 100 K, T vib(0,1) = 1985 ± 200 K, while the flow in the shock layer was near equilibrium, T rot = 3730 ± 400 K, T vib(0,1) = 4000 ± 200 K [58]. Broadband CARS has also been used to determine vibrational relaxation rates of diatomic molecules, inferred from vibrational and rotational temperatures measured in a supersonic expansion in a shock tunnel, such as has been done by Kozlov et al [59] for vibrational relaxation of CO by H atoms.…”

Section: Vibrational Cars: Vibrational and Rotational Temperatures Inmentioning

confidence: 99%

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Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Lempert

Adamovich

2014

J. Phys. D: Appl. Phys.

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The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed. 45 I 2

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Section: Vibrational Cars: Vibrational and Rotational Temperatures Inmentioning

confidence: 99%

Section: Vibrational Cars: Vibrational and Rotational Temperatures Inmentioning

confidence: 99%

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Lempert

Adamovich

2014

J. Phys. D: Appl. Phys.

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“…Therefore, particularly in the case of impulse facilities of short duration such as reflected shock tunnels and expansion tubes, knowledge of caloric quantities of the stagnated test gas prior to nozzle expansion is highly desirable in order to accurately determine nozzle inlet conditions and eventually increase the accuracy of calculated freestream quantities [10].…”

Section: Introductionmentioning

confidence: 99%

In situ nozzle reservoir thermometry by laser-induced grating spectroscopy in the HELM free-piston reflected shock tunnel

2021

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Experimental determination of test gas caloric quantities in high-enthalpy ground testing is impeded by excessive pressure and temperature levels as well as minimum test timescales of short-duration facilities. Yet, accurate knowledge of test gas conditions and stagnation enthalpy prior to nozzle expansion is crucial for a valid comparison of experimental data with numerical results. To contribute to a more accurate quantification of nozzle inlet conditions, an experimental study on non-intrusive in situ measurements of the post-reflected shock wave stagnation temperature in a large-scale free-piston reflected shock tunnel is carried out. A series of 20 single-shot temperature measurements by resonant homodyne laser-induced grating spectroscopy (LIGS) is presented for three low-/medium-enthalpy conditions (1.2–2.1 MJ/kg) at stagnation temperatures 1100–1900 K behind the reflected shock wave. Prior limiting factors resulting from impulse facility recoil and restricted optical access to the high-pressure nozzle reservoir are solved, and advancement of the optical set-up is detailed. Measurements in air agree with theoretical calculations to within 1–15%, by trend reflecting greater temperatures than full thermo-chemical equilibrium and lesser temperatures than predicted by ideal gas shock jump relations. For stagnation pressures in the range 9–22 MPa, limited influence due to finite-rate vibrational excitation is conceivable. LIGS is demonstrated to facilitate in situ measurements of stagnation temperature within full-range ground test facilities by superior robustness under high-pressure conditions and to be a useful complement of established optical diagnostics for hypersonic flows.

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“…The first group of sensors are time detectors with laser [9], cinematography [10], X-ray flash [11], electromagnetic sensors, shadowgraph, high-speed cameras, Schlieren [12,13], and other innovative techniques [14], which are also visible in some of these methods such as the high-speed cameras, Schlieren, and some laser methods, as well as the shape of the wavefront. In all of these methods, the need for an external supply is to receive changes from the sensor.…”

Section: Introductionmentioning

confidence: 99%

An Optical Measurement System to Measure Velocity and Provide Shock Wave Pressure Diagrams

Zamani

Samimi

Sardarzadeh

et al. 2020

IJE

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This paper introduces an optical measurement system for shock wave characteristics. The system works by mounting a metal plate attached to spring mounts against the shock wavefront. This set is sealed and can plot the shock wave pressure diagram by measuring plate's displacement, radiation and changing the reflection of light during shock wave conflict, and converting these optical data to voltage. In the experiments with the optical system, there was no delay time in the wave impact response. Using the optical system and the fixture designed and built, it is also possible to measure the velocity of moving objects and monitor the planar shock wave formation in addition to the shock wave velocity. Then the calibration was performed with the help of a standard piezoresistive sensor in a cold diaphragm shock tube, with a pressure of 5.5 to 12.5 bar by performing 12 tests. Relations and figures for output voltage and shock pressure are also explained.

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Rotational and vibrational temperature measurements using CARS in a hypervelocity shock layer flow and comparisons with CFD calculations

Cited by 18 publications

References 20 publications

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

In situ nozzle reservoir thermometry by laser-induced grating spectroscopy in the HELM free-piston reflected shock tunnel

An Optical Measurement System to Measure Velocity and Provide Shock Wave Pressure Diagrams

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