Collective light scattering as non-particle laser velocimetry

Bonnett, J P; Grésillon, D.; Cabrit, B.; Frolov, V. A.

doi:10.1088/0957-0233/6/6/002

Cited by 15 publications

(15 citation statements)

References 6 publications

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“…A comparison between CLS spectra and LDV has been made by Bonnet et al (1995). The experiment was done in a wind tunnel where two atmospheric flows of different parallel velocities merged into a sheared-flow supersonic mixing layer.…”

Section: Cls Spectrum and Laser Doppler Velocimetrymentioning

confidence: 99%

Turbulence cascade and dynamical exchange between spatial scales

Honoré

Grésillon

2000

J. Fluid Mech.

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The information exchange dynamics between different spatial scales of a turbulent field is experimentally investigated, with particular reference to the energy cascade process. This is done by use of the collective light scattering (CLS) diagnostic, a new optical setting tuned for the observation of atomic number density fluctuations at macroscopic scales. A two-channel scattering device is described that provides simultaneously the fluctuations at two different spatial scales. The turbulent system is an axisymmetric air jet. With this system, time correlations between signal amplitudes for two different scales show a characteristic time width. This time does not depend on the observed scales: it is close to the turbulence production time. Nevertheless, signal amplitude autocorrelation shows a shorter characteristic time. The autocorrelation time scaling law behaves almost like the eddy turnover time from Kolmogorov theory.

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Section: Cls Spectrum and Laser Doppler Velocimetrymentioning

confidence: 99%

Turbulence cascade and dynamical exchange between spatial scales

Honoré

Grésillon

2000

J. Fluid Mech.

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“…Overlapping the segments by 50% provided a near maximum reduction in the variance in the spectral estimate 27 . The resulting power spectra from the Rayleigh scattering measurements provide fluctuation information up to half of the sampling frequency (5,8,or 16 kHz), and the sum of all points in the spectra is equivalent to the mean square fluctuations. A common numerical processing method used to eliminate noise from power spectra involves simply subtracting the noise floor from the spectrum.…”

Section: B Power Spectral Calculationsmentioning

confidence: 99%

“…Eckbreth 1 provides the details of several molecular scattering based techniques, such as Coherent AntiStokes Raman Spectroscopy (CARS), spontaneous Raman and Rayleigh scattering, and Laser Induced Fluorescence (LIF), with an emphasis on their use in combustion applications. Other molecular-based techniques include laserinduced gratings 2,3 , filtered Rayleigh scattering 4 , collective light scattering 5 , and molecular flow tagging techniques 6 . The most common particle-based techniques are Laser Doppler Velocimetry (LDV) 7 , Particle Image Velocimetry (PIV) 8 , and Planar Doppler Velocimetry (PDV) 9 .…”

Section: Introductionmentioning

confidence: 99%

Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

Mielke

Elam

Sung

2008

46th AIAA Aerospace Sciences Meeting and Exhibit

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[Abstract] A molecular Rayleigh scattering technique is developed to measure timeresolved gas velocity, temperature, and density in unseeded gas flows at sampling rates up to 32 kHz. A high power continuous-wave laser beam is focused at a point in an air flow field and Rayleigh scattered light is collected and fiber-optically transmitted to the spectral analysis and detection equipment. The spectrum of the light, which contains information about the temperature and velocity of the flow, is analyzed using a Fabry-Perot interferometer. Photomultipler tubes operated in the photon counting mode allow high frequency sampling of the circular interference pattern to provide time-resolved flow property measurements. Mean and rms velocity and temperature fluctuation measurements in both an electrically-heated jet facility with a 10-mm diameter nozzle and also in a hydrogen-combustor heated jet facility with a 50.8-mm diameter nozzle at NASA Glenn Research Center are presented.

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“…Based on well-known (Ref [6][7][8][9][10][11][12] scattering techniques, a faster and more stable experiment has been developed to measure drift velocity and relative density distribution within a flow.…”

Section: Introductionmentioning

confidence: 99%

Velocity Diagnostics for Gas Velocity Distributions in Cold Gas and Plasma Spraying Using Non-Resonant Laser Scattering

et al. 2010

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In cold spray and thermal spray applications, one of the primary factors affecting coating deposition is the location where particles are injected into the gas jet. Therefore, a detailed knowledge of the gas flow distribution at that location is required. Use of non-resonant laser scattering allows to spatially resolve the distribution of drift velocity and mass density within the flow, particularly, at locations close to the injector. Based on this technique, this article presents a new diagnostic to locally measure drift velocity and relative mass density distribution of a gas stream. Its application is mainly focused on cold gas flows, where velocity measurements in a supersonic nozzle, obtained by means of laser scattering correlate well with theoretical calculations and particle image velocimetry (PIV) experimental results.

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Collective light scattering as non-particle laser velocimetry

Cited by 15 publications

References 6 publications

Turbulence cascade and dynamical exchange between spatial scales

Turbulence cascade and dynamical exchange between spatial scales

Time-Resolved Rayleigh Scattering Measurements in Hot Gas Flows

Velocity Diagnostics for Gas Velocity Distributions in Cold Gas and Plasma Spraying Using Non-Resonant Laser Scattering

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