The application of laser-induced Rayleigh light scattering to the study of turbulent mixing

Pitts, William; Kashlwagi, T.

doi:10.6028/nbs.ir.83-2641

Cited by 18 publications

(49 citation statements)

References 34 publications

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“…The following section (2) proposed which is in qualitative agreement with the experimental findings.…”

supporting

confidence: 80%

“…Such flows are of interest for several reasons. Among these are: (1) the axisymmetric symmetry simplifies some analyses, (2) these flows are easily generated in a laboratory environment, (3) many practical systems employ such flows, and (4) these flows can serve as simple analogs for more complicated flows. …”

Section: Review Of Axisymmetric Jetsmentioning

confidence: 99%

“…Laser-induced Rayleigh light scattering [1][2][3][4] was employed as the real-time, spatially-resolved concentration probe for these binary gas mixtures.…”

mentioning

confidence: 99%

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Effects of global density and Reynolds number variations on mixing in turbulent, axisymmetric jets

Pitts¹

1986

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“…The following section (2) proposed which is in qualitative agreement with the experimental findings.…”

supporting

confidence: 80%

Section: Review Of Axisymmetric Jetsmentioning

confidence: 99%

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Effects of global density and Reynolds number variations on mixing in turbulent, axisymmetric jets

Pitts¹

1986

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“…The same can be said for virtually all studies of mixing in gaseous jets, which have focused largely on single point measurements of the conserved scalar field (e.g. Becker, Hottel & Williams 1967;Antonia et al 1975;Birch et al 1978;Pitts & Kashiwagi 1984). Moreover, few of these measurements have had the necessary spatial or temporal resolution to distinguish the full range of scales involved in the conserved scalar field.…”

Section: Small Scales and Molecular Mixingmentioning

confidence: 99%

Mixing at large Schmidt number in the self-similar far field of turbulent jets

1990

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We present results from an experimental investigation of turbulent transport and molecular mixing of a Sc S 1 conserved scalar in the fully developed self-similar far field of a steady, axisymmetric, momentum-driven, free turbulent jet issuing into a quiescent medium. Our experiments cover the axial range from the jet exit to 350 diameters downstream, and span the range of Reynolds numbers from 1500 to 20 000. Flow visualizations of the scalar concentration field directly verify the presence of an underlying characteristic large-scale organization in the jet far field essentially consistent with a simplified conceptual picture proposed in an earlier study (Dahm & Dimotakis 1987). High-resolution imaging measurements of successive instantaneous scalar concentration profiles in the jet support the presence of such a large-scale organization and provide details of its implications for mixing. These results also establish the proper similarity scaling for the mean concentration in the jet far field and give the scaling constant on the jet centreline as 5.4. We also present conserved scalar concentration p.d.f.s throughout the jet far field, and introduce a chemical reaction method for measuring the p.d.f.s with potentially molecular resolution. The amount of unmixed ambient fluid that reaches the jet centreline is found to decrease with increasing Reynolds number over the range investigated. The distribution of mixed fluid compositions in the concentration p.d.f. also appears to change over this range of Reynolds numbers, indicating that some aspects of large Schmidt number mixing in the jet far field have not yet become Reynolds number independent.

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“…, who used a specialized fuel mixture to keep the Rayleigh scattering cross section constant throughout the flame. LRS has also been used in heat transfer studies [2] and fluid mixing experiments [3]. LRS has the advantage of simplicity but the disadvantage of weak signal strength, which can be quickly overwhelmed by Mie scattering from solid surfaces, room particulate and soot.…”

Section: Frs For Temperature Imaging In Fire and Combustion Applicationsmentioning

confidence: 99%

Filtered Rayleigh scattering diagnostic for multi-parameter thermal-fluids measurements : LDRD final report.

Beresh¹,

Grasser²,

Kearney³

et al. 2004

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Simulation-based life-cycle-engineering and the ASCI program have resulted in models of unprecedented size and fidelity. The validation of these models requires high-resolution, multiparameter diagnostics. Within the thermal/fluids disciplines, the need for detailed, high-fidelity measurements exceeds the limits of current Engineering Sciences capabilities and severely tests the state of the art; therefore, a diagnostic development effort is warranted. The focus of this LDRD is the development and application of filtered Rayleigh scattering (FRS) for highresolution, nonintrusive measurement of gas-phase velocity and temperature. This multiparameter technique adds significant experimental capability to several Sandia programs including Fire Science and Technology (FS&T) and Aerosciences programs in the Engineering Sciences Center (9100) and Reacting Flow Research at the Combustion Research Facility (8300).With FRS, the flow is laser-illuminated and Rayleigh scattering from naturally occurring sources is detected through a molecular filter. The filtered transmission may be interpreted to yield point or planar measurements of three-component velocities and/or thermodynamic state. Different experimental configurations may be employed to obtain compromises between spatial resolution, time resolution, and the quantity of simultaneously measured flow variables. This capacity for multi-parameter, non-intrusive instrumentation represents an unprecedented advance beyond presently available techniques in the Engineering Sciences Center and in the larger scientific arena. Furthermore, measurements may be made using naturally occurring scattering centers, eliminating potentially intractable difficulties associated with particulate or chemical seeding in a hypersonic or reacting environment. Molecular-filter absorption of scattered light from solid boundaries also makes FRS advantageous for detailed boundary-layer measurements. 4These advantages make FRS an attractive alternative to developed techniques and offer a substantial payoff impacting multiple thermal/fluids disciplines. Moreover, a virtually identical experimental configuration may be utilized for both aerodynamic and thermal diagnostic applications simply by adjusting the laser and molecular filter. These measurements are ideally suited for use in production-scale facilities, where many other techniques are difficult to implement.In this report, we present the results of a three-year LDRD-funded effort to develop FRS combustion thermometry and Aerosciences velocity measurement systems. The working principles and details of our FRS opto-electronic system are presented in detail. For combustion thermometry we present 2-D, spatially correlated FRS results from nonsooting premixed and diffusion flames and from a sooting premixed flame. The FRS-measured temperatures are accurate to within ±50 K (3%) in a premixed CH 4 -air flame and within ±100 K for a vortexstrained diluted CH 4 -air diffusion flame where the FRS technique is severely tested by large variation ...

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The application of laser-induced Rayleigh light scattering to the study of turbulent mixing

Abstract: The kurtosis of the methane concentration distribution on the jet centerline is plotted as a function of z/r Q Examples of correlation functions and power spectra for methane concentration fluctuations at three different axial downstream distances in a methaneair jet.

Cited by 18 publications

References 34 publications

Effects of global density and Reynolds number variations on mixing in turbulent, axisymmetric jets

Effects of global density and Reynolds number variations on mixing in turbulent, axisymmetric jets

Mixing at large Schmidt number in the self-similar far field of turbulent jets

Filtered Rayleigh scattering diagnostic for multi-parameter thermal-fluids measurements : LDRD final report.

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