Molecular velocity imaging of supersonic flows using pulsed planar laser-induced fluorescence of NO

Paul, Phillip H.; Lee, M. P.; Hanson, Ronald K.

doi:10.1364/ol.14.000417

Cited by 107 publications

(25 citation statements)

References 5 publications

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“…Tuned-frequency schemes, however, are less susceptible to systematic error 16 and the dynamic range of the technique is not limited by the finite width of the spectral line or laser line as is with fixed-frequency schemes. 17 In the current study, Doppler-shift based velocimetry was used to obtain quantitative distributions of radial velocity for two flow conditions simulating a 10.8 MJ/kg Mars atmosphere (Run 114) and 6.5 MJ/kg Earth atmosphere (Run 85). By scanning the laser over a small wavelength range, the excitation spectrum of the relatively well-isolated Q 1 (13) transition of NO was captured on a series of images using the Princeton Instruments PIMAX-2 intensified CCD camera with 512 x 512 pixel resolution.…”

Section: E Doppler Velocimetry For Radial Velocity Measurementsmentioning

confidence: 99%

Nitric Oxide PLIF Measurements in the Hypersonic Materials Environmental Test System (HYMETS)

Inman

Bathel

Johansen

et al. 2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A nonintrusive laser-based measurement system has been applied for the first time in the HYMETS (Hypersonic Materials Environmental Test System) 400 kW arc-heated wind tunnel at NASA Langley Research Center. Planar laser-induced fluorescence of naturally occurring nitric oxide (NO) has been used to obtain instantaneous flow visualization images, and to make both radial and axial velocity measurements. Results are presented at selected facility run conditions, including some in simulated Earth atmosphere (75% nitrogen, 20% oxygen, 5% argon) and others in simulated Martian atmosphere (71% carbon dioxide, 24% nitrogen, 5% argon), for bulk enthalpies ranging from 6.5 MJ/kg to 18.4 MJ/kg. Flow visualization images reveal the presence of large scale unsteady flow structures, and indicate nitric oxide fluorescence signal over more than 70% of the core flow for bulk enthalpies below about 11 MJ/kg, but over less than 10% of the core flow for bulk enthalpies above about 16 MJ/kg. Axial velocimetry was performed using molecular tagging velocimetry (MTV). Axial velocities of about 3 km/s were measured along the centerline. Radial velocimetry was performed by scanning the wavelength of the narrowband laser and analyzing the resulting Doppler shift. Radial velocities of ±0.5km/s were measured.

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Section: E Doppler Velocimetry For Radial Velocity Measurementsmentioning

confidence: 99%

Nitric Oxide PLIF Measurements in the Hypersonic Materials Environmental Test System (HYMETS)

Inman

Bathel

Johansen

et al. 2011

49th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…With slightly more experimental effort, the assumption of a symmetric ow eld could be relaxed. For example, counterpropagating laser sheets 17 can be used to determine the component of the ow velocity in the direc- 16 tion of the laser sheet without assuming ow symmetry. The method could be extended to measure more components of the velocity eld by directing additional laser sheets into the ow eld.…”

Section: Discussionmentioning

confidence: 99%

“…The two methods rely on the laser linewidth .1º L / being much broader than, 17 or much narrower than, 13 the transition's absorption linewidth .1º T / throughout the ow eld. However, a signi cant complication in the current experiment is that the pressure and temperature variations throughout the image are large, ranging from 5 kPa and 400 K in the freestream to approximately an atmosphere and 1600 K in the shocklayer region.…”

Section: B Fluorescence Velocimetrymentioning

confidence: 99%

Fluorescence Velocimetry of the Hypersonic, Separated Flow over a Cone

et al. 2001

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Planar laser-induced uorescence of nitric oxide is used to measure a component of the velocity eld for the Mach 7 ow around a 30-deg half-angle, 50-mm-diam cone mounted to a long, 38-mm-diam shaft, or "sting." Transverse velocities are measured in the freestream, the shock layer, and the separated region at the junction between the cone and the sting. For most of the ow eld, the uncertainty of the measurements is between § § 50 and § § 100 m/s for velocities ranging from ¡ 300 to 1300 m/s, corresponding to a minimum uncertainty of § § 5%. The measurements are compared with the commercial computational uid dynamics (CFD) code CFD-FASTRAN TM . The agreement between the theoretical model and the experiment is reasonably good. CFD accurately predicts the size and shape of the shock layer and separated region behind the cone as well as the magnitude of the gas velocity near the reattachment shock. However, the magnitude of the velocity in the shock layer and gas expansion differ somewhat from that predicted by CFD. The discrepancies are attributed to a small systematic error associated with laser-beam attenuation and also to inexact modeling of the ow eld by CFD.

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“…1,2 What is novel in this new class of diagnostic techniques, however, is that they do not depend on a fluorescent species being present in the flow: instead they operate with light scattered by particles in the flow with the absorption species located in the detection system.…”

Section: General Description Of Pdvmentioning

confidence: 99%

Filtered Rayleigh Scattering Velocimetry for Wind Tunnel Applications

Crafton¹,

Elliott²,

Carter³

et al. 2004

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Molecular velocity imaging of supersonic flows using pulsed planar laser-induced fluorescence of NO

Cited by 107 publications

References 5 publications

Nitric Oxide PLIF Measurements in the Hypersonic Materials Environmental Test System (HYMETS)

Nitric Oxide PLIF Measurements in the Hypersonic Materials Environmental Test System (HYMETS)

Fluorescence Velocimetry of the Hypersonic, Separated Flow over a Cone

Filtered Rayleigh Scattering Velocimetry for Wind Tunnel Applications

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