Velocimetry Using Graphite Tracer Particles in a Scramjet Flowpath (Invited)

Kirik, Justin W.; Goyne, Christopher P.; McDaniel, James C.; Rockwell, Robert D.; Johnson, Ryan F.; Chelliah, Harsha K.

doi:10.2514/6.2015-0355

Cited by 11 publications

(4 citation statements)

References 35 publications

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“…The laser sheet is inserted into the test section through a fused silica window and is coplanar with the tunnel center plane while its focus coincides with the center of the imaging field of view. Graphite nanoflakes of mean length 1.1 µm and thickness 16 nm [33] are levitated in a fluidized bed seeder [34] and injected at 35 psi above tunnel pressure in the isolator, upstream of the fuel injectors and on the centerline. The cross-flow jet penetrates approximately halfway into the duct and is thoroughly mixed with the freestream by turbulent convection amplified by the isolator shock train.…”

Section: Summary and Hardware Specificationsmentioning

confidence: 99%

“…These tracers prevent window fouling better than other typical PIV tracer materials which suppressed optical access (Al 2 O 3 , TiO 2 , SiO 2 , [35,36]) through a combination of lower adhesion rates and combustion in stagnant areas. The flakes flow tracking ability is predicted to be adequate based on theoretical analysis using its Stokes number [33]. The flake nature of the tracers is necessary due to unavailability of spherical graphite particles with adequate Stokes numbers.…”

Section: Tracer Properties and Seedingmentioning

confidence: 99%

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High-resolution PIV for characterization of the inflow to a cavity flameholder

Lieber

Goyne

Gibbons

2020

Meas. Sci. Technol.

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A methodology for the implementation of high-resolution, two-component, two-dimensional particle image velocimetry (PIV) in a high-speed, high-enthalpy flow is presented and demonstrated. The objective is to resolve the finer scales of combusting flows at high subsonic Mach numbers for accurate boundary conditions quantification for direct numerical simulations. A three-pronged approach consists of finding a near-optimum setup specific to the experiment, enhancing the raw signal with a novel filter for high-speed flows based on a logarithmic transform, and quantifying uncertainties. The methodology effectiveness is demonstrated with synthetic PIV, real PIV, and comparison with numerical simulations.

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Section: Summary and Hardware Specificationsmentioning

confidence: 99%

Section: Tracer Properties and Seedingmentioning

confidence: 99%

High-resolution PIV for characterization of the inflow to a cavity flameholder

Lieber

Goyne

Gibbons

2020

Meas. Sci. Technol.

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“…In this paper, a dual-mode scramjet fueled with ethylene (C2H4) is investigated in the same University of Virginia facility. A frequency-doubled tunable laser was tuned at 283 nm to excite a specific absorption transition of OH; images of OH fluorescence were recorded both perpendicular to the freestream (cross-plane view) and parallel to the freestream (stream-wise view); 4 planes were recorded for the cross-plane view at the same location and test conditions of the subsequent particle image velocity (PIV) 15 and width enhanced coherent anti-Stokes Raman scattering (WIDECARS) 16 measurements of C2H4-air combustion in the same facility. Scans through all the imaging planes were also recorded for all the facility conditions.…”

Section: Figure 1: Lif Energy Diagrammentioning

confidence: 99%

OH PLIF Visualization of a Premixed Ethylene-fueled Dual-Mode Scramjet Combustor

Cantu

Gallo

Cutler

et al. 2016

54th AIAA Aerospace Sciences Meeting

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Hydroxyl radical (OH) planar induced laser fluorescence (PLIF) measurements have been performed in a small-scale scramjet combustor at the University of Virginia Aerospace Research Laboratory at nominal simulated Mach 5 enthalpy. OH lines were carefully chosen to have fluorescent signal that is independent of pressure and temperature but linear with mole fraction. The OH PLIF signal was imaged in planes orthogonal to and parallel to the freestream flow at different equivalence ratios. Flameout limits were tested and identified. Instantaneous planar images were recorded and analyzed to compare the results with width increased dual-pump enhanced coherent anti-Stokes Raman spectroscopy (WIDECARS) measurements in the same facility and large eddy simulation/Reynolds average Navier-Stokes (LES/RANS) numerical simulation. The flame angle was found to be approximately 10 degrees for several different conditions, which is in agreement with numerical predictions and measurements using WIDECARS. Finally, a comparison between NO PLIF non-combustion cases and OH PLIF combustion cases is provided: the comparison reveals that the dominant effect of flame propagation is freestream turbulence rather than heat release and concentration gradients.

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“…The experiments described in this paper have resulted in databases that are currently under development and, through collaboration with the NCHCCP, are leading to the validation of advanced time averaged and time accurate numerical models [8]. Details and status of the CARS and PIV measurements are presented elsewhere by Gallo and Kirik, respectively [9,10]. Edwards presents results of the numerical modeling efforts [11].…”

Section: Introductionmentioning

confidence: 99%

Development of a Premixed Combustion Capability for Dual-Mode Scramjet Experiments (Invited)

Rockwell

Goyne

Rice

et al. 2015

53rd AIAA Aerospace Sciences Meeting

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Hypersonic air-breathing engines rely on scramjet combustion processes, which involve high speed, compressible, and highly turbulent flows. The combustion environment and the turbulent flames at the heart of these engines are difficult to simulate and study in the laboratory under well controlled conditions. Typically, wind-tunnel testing is performed that more closely approximates engine testing rather than a careful investigation of the underlying physics that drives the combustion process. The experiments described in this paper, along with companion data sets being developed separately, aim to isolate the chemical kinetic effects from the fuel-air mixing process in a dual-mode scramjet combustion environment. A unique fuel injection approach is taken that produces a uniform fuel-air mixture at the entrance to the combustor. This approach relies on the precombustion shock train upstream of the dual-mode scramjet combustor. A stable ethylene flame anchored on a cavity flame holder with a uniformly mixed combustor inflow has been achieved in these experiments allowing numerous companion studies involving coherent anti-Stokes Raman scattering (CARS), particle image velocimetry (PIV), and planar laser induced fluorescence (PLIF) to be performed.

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Velocimetry Using Graphite Tracer Particles in a Scramjet Flowpath (Invited)

Cited by 11 publications

References 35 publications

High-resolution PIV for characterization of the inflow to a cavity flameholder

High-resolution PIV for characterization of the inflow to a cavity flameholder

OH PLIF Visualization of a Premixed Ethylene-fueled Dual-Mode Scramjet Combustor

Development of a Premixed Combustion Capability for Dual-Mode Scramjet Experiments (Invited)

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