Hypersonic wake measurements behind a slender cone using FLEET velocimetry

Zhang, Yibin; Richardson, Daniel; Beresh, Steven J.; Casper, Katya M.; Soehnel, Melissa Marie; Henfling, John F.; Spillers, Russell Wayne

doi:10.2514/6.2019-3381

Cited by 6 publications

(8 citation statements)

References 30 publications

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“…An arbitrary streamwise position of the laser within the image is provided by µ 0 . This modeling approach is supported by previous fitting efforts that have shown a double-Gaussian approach to FLEET velocimetry to be accurate [15,16,38]. A one-dimensional fluid diffusion model was used to represent the diffusion of the FLEET emission, which was fit at various time delays to identify a line width as a function of time σ(t).…”

Section: Synthetic Datamentioning

confidence: 89%

“…Work by Limbach showed heating of the gas caused by traditional FLEET diagnostics [7,14], motivating the development of Selective two-photon absorptive resonance femtosecond laser electronic excitation tagging (STARFLEET). STARFLEET reduces the thermal energy deposited in the flow field while simultaneously increasing the signal and emission lifetime [15][16][17]. FLEET has been successfully applied in the AEDC Hypervelocity Wind Tunnel and Sandia's Hypersonic Wind Tunnel which both use a working fluid of pure nitrogen [15,18].…”

Section: Introductionmentioning

confidence: 99%

“…STARFLEET reduces the thermal energy deposited in the flow field while simultaneously increasing the signal and emission lifetime [15][16][17]. FLEET has been successfully applied in the AEDC Hypervelocity Wind Tunnel and Sandia's Hypersonic Wind Tunnel which both use a working fluid of pure nitrogen [15,18]. Experiments in the AFRL Mach-6 Ludwieg tube has further shown that FLEET diagnostics can produce reliable estimates of mean velocity in a hypersonic tunnel with a working fluid of air [19].…”

Section: Introductionmentioning

confidence: 99%

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Hypersonic FLEET velocimetry and uncertainty characterization in a tripped boundary layer

Pehrson,

Leonov,

Melone

et al. 2023

Meas. Sci. Technol.

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Femtosecond laser electronic excitation tagging (FLEET) velocimetry is applied in a hypersonic boundary layer behind an array of turbulence-inducing trips. One-dimensional mean velocity and root-mean-square (RMS) of velocity fluctuation profiles are extracted from FLEET emissions oriented across a test article and through a boundary layer in two test campaigns spanning 21 tunnel runs. The Texas A&M University Actively Controlled Expansion tunnel in which FLEET was performed operates near Mach 6.0 with Reynolds number near 6 ×106 m-1 and a working fluid of air at a density near 2.5 × 10-2 kg/m3. Calibration curves are generated using synthetic images to estimate the error in the mean velocity due to emission decay and the error in the RMS velocity fluctuation due to imprecision. The boundary layer behind an array of turbulence-inducing trips is documented to show the breakdown of coherent structures. FLEET velocimetry is compared to the tunnel data acquisition system, Vibrationally Excited Nitric Oxide Monitoring (VENOM) results, and Reynolds-Averaged Navier-Stokes Computational Fluid Dynamics to verify results.

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Section: Synthetic Datamentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hypersonic FLEET velocimetry and uncertainty characterization in a tripped boundary layer

Pehrson,

Leonov,

Melone

et al. 2023

Meas. Sci. Technol.

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“…FLEET velocimetry has been also demonstrated in other complex flow environments, such as in combustion (DeLuca et al 2017), in the NASA Langley high-pressure cryogenic tunnel (Burns et al 2018a(Burns et al , 2018b, in bladeless wind turbines (Fisher et al 2020a), in the Quiet Mach 6 tunnel at Purdue (Fisher et al 2021), in a high-enthalpy arc-jet tunnel (UTA 2020) and in the wake of a cone at Mach 8 at Sandia (Zhang et al 2019). Multiple line FLEET has been applied at Sandia (Zhang et al.…”

Section: Femtosecond Laser Electronic Excitation Tagging (Fleet)mentioning

confidence: 99%

Localized time accurate sampling of nonequilibrium and unsteady hypersonic flows: methods and horizons

Miles

Dogariu

Dogariu³

2021

Exp Fluids

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Modern “non-intrusive” optical methods are providing revolutionary capabilities for diagnostics of hypersonic flow fields. They generate accurate information on the performance of ground test facilities and provide local time accurate measurements of near-wall and off-body flow fields surrounding hypersonic test articles. They can follow the true molecular motion of the flow and detect nonequilibrium states and gas mixtures. They can be used to capture a wide range of turbulent scales and can produce highly accurate velocity, temperature and density measurements as well as time-frozen images that provide intuitive understanding of flow phenomena. Recent review articles address many of these methods and their applications. The methods highlighted in this review are those that have been enabled or greatly improved by new, versatile laser systems, particularly including kHz rate femtosecond lasers and MHz rate pulse burst lasers. Although these methods can be applied to combusting environments, the focus of this review is on external high Mach number flows surrounding test articles and wind tunnel core flow properties. The high repetition rates enable rapid time evolving flows to be analyzed and enable the collection of large data sets necessary for statistical analysis. Future capabilities based on the use of atomic vapor filters and on frequency tunable, injection locked MHz rate lasers are promising.

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“…FLEET is an unseeded molecular tagging method capable of nonintrusive measurements of velocity [1][2][3], temperature [4], density [5] and species concentration [6] for gases containing molecular nitrogen. The method has been employed in many types of flows, including turbulent [7], cryogenic [8,9], highspeed [10][11][12][13], combusting [14,15], as well as highly unsteady flows with subsonic through supersonic components [16].…”

Section: Introductionmentioning

confidence: 99%

Effect of low temperatures and pressures on signal, lifetime, accuracy and precision of femtosecond laser tagging velocimetry

Peters¹,

Burns²,

Miles³

et al. 2020

Meas. Sci. Technol.

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Femtosecond laser electronic excitation tagging velocimetry is experimentally characterized in pure nitrogen at pressures (0.228-101 kPa) and temperatures (72-298 K) relevant to high-speed ground testing. Evaluated metrics of performance include signal intensity/lifetime and velocity accuracy/precision. A fast-framing camera lens-coupled to a bandpass-filtered image intensifier acquired data at six principal time delays (0.1-5.0 µs). Results show signal intensity depends primarily on density and secondarily on temperature. Relative to atmospheric conditions, signal intensity is optimized at reduced densities and cryogenic temperatures. In agreement with previous experiments, the density dependence breaks down at extended time delays. Signal lifetime depends largely on density with a mild to moderate inverse correlation to initial signal strength. In contrast to previous work in pure nitrogen at above atmospheric densities, initial signal and lifetime exhibit different, more complicated trends at sub-atmospheric densities. Although accuracy lacks clear thermodynamic dependencies, precision strongly depends on density and temperature, largely driven by its more fundamental (though inverse) relationship to signal intensity. Precision also inversely depends on the length of the time interval used to determine velocity, in agreement with previous studies. Normalized accuracies and precisions of less than a percent and a few percent, respectively, are obtained in the supersonic free jet.

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Hypersonic wake measurements behind a slender cone using FLEET velocimetry

Cited by 6 publications

References 30 publications

Hypersonic FLEET velocimetry and uncertainty characterization in a tripped boundary layer

Hypersonic FLEET velocimetry and uncertainty characterization in a tripped boundary layer

Localized time accurate sampling of nonequilibrium and unsteady hypersonic flows: methods and horizons

Effect of low temperatures and pressures on signal, lifetime, accuracy and precision of femtosecond laser tagging velocimetry

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