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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Rodrigues, Neil S. Burns, Ross A. Tyrrell, Olivia K. Danehy, Paul M. NASA Langley Research Center Advanced Measurements and Data Systems Branch HamptonVA23681 United States ViGYAN Inc. Advanced Measurements and Data Systems Branch HamptonVA23666 United States

ISBN: (纸本)9781624107238

Planar laser-induced fluorescence (PLIF) flow visualization was used to examine the spatial evolution for the wall-jet formed by an impinging supersonic jet in a large-scale vacuum environment. This canonical configuration is representative of the plume-surface interaction (PSI) induced by a rocket exhaust plume impinging on the planetary surface at lunar-relevant and Martian-relevant environments. PLIF flow visualization of the very low-density environment (as low as ~0.006% of standard atmospheric density) was performed using seeded nitric oxide in a nitrogen flow at three test conditions. Two conditions are representative of the lunar environment, and one is representative of the Martian environment. The combined images from two simultaneous PLIF views were used to construct a 2D slice of the flowfield spanning approximately 150 mm in height (determined by the laser sheet) and 500 mm in width (determined by the camera views). The three test conditions showed different behavior for the wall-jet, largely due to the different levels of lifting above the surface and the appearance of a physical process similar to a Kelvin–Helmholtz instability for the Martian-relevant case, which appeared to create a dramatic expansion of the wall-jet height with increased radial distance. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Atmospheric density

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Towards Simultaneous Multi-Parameter measurements Using Burst-Mode FrequencyScanning Planar Laser-Induced Fluorescence

Towards Simultaneous Multi-Parameter Measurements Using Burs...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Braun, Amanda M. Rodrigues, Neil S. Danehy, Paul M. Advanced Measurements and Data Systems Branch NASA Postdoctoral Program at NASA Langley Research Center HamptonVA23681 United States Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA23681 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

While planar laser-induced fluorescence (PLIF) can provide valuable flow visualization, there are many challenges in extracting quantitative measurements from the fluorescence intensity. To overcome the multi-parameter dependence of the signal intensity, frequencyscanning planar laser-induced fluorescence (FS-PLIF) provides the potential for 2D temperature, pressure, and velocity measurements by spectrally resolving the excitation spectrum of one or more fluorescence transitions to extract the Doppler shift, Doppler- and collisional-broadening of absorption lines, and the relative signal intensities of multiple transitions. This work aims to characterize a burst-mode FS-PLIF system consisting of a Spectral Energies, LLC burst-mode laser coupled with a Spectral Energies, LLC optical parametric oscillator using nitric oxide (NO) static pressure cell measurements. The effect of the OPO cavity on intensity fluctuations during frequency-scanning is investigated. A NO PLIF model is implemented to investigate the feasibility of property measurements using single-and two-NO-line scans. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Optical parametric oscillators

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Modification of Mach 6 Freestream Flow by Pitot Probe Bow Shock as Measured by Line FLDI and SAFS

Modification of Mach 6 Freestream Flow by Pitot Probe Bow Sh...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Weisberger, Joshua M. Herring, Gregory C. Page, Wayne E. Bathel, Brett F. Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA23681 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

measurements of the flow in front of flat-face Pitot probes in NASA Langley Research Center’s 20-Inch Mach 6 Air Tunnel were made using a 35-point line focused laser differential interferometer (FLDI), a two-point FLDI, and a self-aligned focusing schlieren system (SAFS). These systems were used to make measurements of flow unsteadiness between the bow shock and Pitot probe face, while also probing the freestream region just upstream of the bow shock. Shock standoff distances from the non-intrusive measurements match closely with analytical solutions using the probe face diameter. Acoustic wave angles and velocities in the freestream compare favorably with direct numerical simulations of a Mach 6 freestream flow, and wave velocities in the post-shock region slow as they approach the probe face. Peak frequencies in the post-shock region as measured by FLDI compare favorably to the estimates computed from the shock standoff distance for most probe diameters. With increasing unit Reynolds number, fluctuation intensities in the post-shock region were attenuated below the intensities of the freestream, with a spectral, spatial, and probe size dependence. Pitot probe power spectral density estimates are presented from the test campaign, which can be compared with FLDI and SAFS data to evaluate the applicability of the transfer functions derived from computational simulations. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Reynolds number

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Wake velocimetry of a sphere-cone model in a Mach 10 air freestream using FLEET

Wake velocimetry of a sphere-cone model in a Mach 10 air fre...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Rodrigues, Neil S. Tyrrell, Olivia K. Hollis, Brian R. Danehy, Paul M. NASA Langley Research Center Advanced Measurements and Data Systems Branch HamptonVA23681 United States Aerothermodynamics Branch NASA Langley Research Center HamptonVA23681 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Velocity measurements in the wake behind a sphere-cone-shaped vehicle wind tunnel model in a Mach 10 hypersonic air flow using femtosecond laser electronic excitation tagging (FLEET) are reported in this work. The FLEET measurements were performed at 1 kHz using a femtosecond laser centered at 800 nm and an ultrahigh-speed intensified camera system. The results reported here are for a single freestream condition corresponding to approximately Re∞/L = 3.6∙106 m-1. The performance of the velocimetry instrument was evaluated in the quiescent test section at conditions relevant to the wake measurements. For velocity measurements in the wake, the FLEET measurement volume was translated to several locations extending radially from the model centerline in the vertical direction and at a streamwise location corresponding to approximately 12 mm from the aft edge of the cylindrical payload. Reverse flow with mean velocities ranging from -12 m/s to -48 m/s were observed in the recirculating region of the wake, whereas hypersonic velocities in the range of 1072 m/s to 1183 m/s were observed in the free shear layer. A velocity uncertainty methodology is also outlined and applied for the reported measurements. The velocity data reported in this work is expected to play a significant role in the validation of computational codes modeling the hard-to-predict separated hypersonic wake. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Femtosecond lasers

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Application of PSP on the SWiFT Model in the National Transonic Facility

Application of PSP on the SWiFT Model in the National Transo...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Watkins, A. Neal Reese, Daniel T. Peak, Sarah M. Goodman, Kyle Z. Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA23666 United States Analytical Mechanics Associates HamptonVA23666 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

This report details the results from a pressure sensitive paint test on a blended/hybrid wing body model conducted at the National Transonic Facility. This test investigated potential instabilities that can occur at low-speed testing conditions at various Reynolds numbers. The model was coated with pressure sensitive paint, and data was collected at various Mach numbers and angles of attack. For this test, typical pitch-pause traverses were performed as well as a novel continuous sweep functionality that provided much greater angle of attack resolution. Results from this test will be presented, including indications of potential instability points in the testing envelope. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Angle of attack

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Recent Progress and Development of Self-Aligned Focusing Schlieren

Recent Progress and Development of Self-Aligned Focusing Sch...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Page, Wayne E. Boyda, Matthew T. Fahringer, Timothy W. Weisberger, Joshua M. Bathel, Brett F. Wernet, Mark P. Heineck, James T. NASA Langley Research Center Advanced Measurements and Data Systems Branch HamptonVA23681 United States NASA Glenn Research Center Optics and Photonics Branch ClevelandOH44135 United States NASA Ames Research Center Experimental Aero-physics Branch Moffett Field CA94035 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

A broad range of developments and applications of self-aligned focusing schlieren (SAFS) systems is presented. The replacement of the Ronchi ruling (RR) with a μLCD was demonstrated with digital SAFS, which provides the ability to modulate the pattern and orientation without physical intervention. Additionally, replacement of the traditional RR with spectral-spatial filters was demonstrated to yield the ability to simultaneously image horizontal and vertical index of refraction gradients using two separate wavelengths. The application of the Scheimpflug principle to SAFS systems enables off-axis imaging and allowed for extended fields-of-view to be captured using a two-camera system. The addition of a plenoptic camera to a baseline SAFS system enables refocusing capabilities, which is demonstrated on two jets offset along the optical axis. Furthermore, application of an event-based camera to SAFS was shown to enable acquisition of sparse, spatio-temporal data. Beyond the listed developments, SAFS was applied to difficult and constraining facilities, such as the National Full-Scale Aerodynamics Complex (NFAC) 80- by 120-ftWind Tunnel and the Thermal Acoustic Engines (TAE) rig at NASA Ames Research Center and NASA Glenn Research Center, respectively. Behavior of Ronchi rulings, Rochon prisms, and the use of quarter-wave plates versus quarter-wave films are evaluated to provide insight for future experimental design of SAFS-systems. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： NASA

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Fiber-Based Multi-Resolution Imaging and Multidimensional X-ray Diagnostics for Ejecta Dynamics in Plume Surface Interactions

Fiber-Based Multi-Resolution Imaging and Multidimensional X-...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： de Carvalho, Lucca M. Karimli, Kanan Verleur, Rees P. Braun, Amanda M. Athmanathan, Venkat Mikhail, N. Slipchenko Meyer, Terrence R. Jiang, Naibo Hsu, Paul Roy, Sukesh Rodrigues, Neil S. Danehy, Paul M. School of Mechanical Engineering Purdue University West LafayetteIN47907 United States Spectral Energies LLC 4065 Executive Dr BeavercreekOH45430 United States NASA Langley Research Center Hampton Advanced Measurements and Data Systems Branch VA23666 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The interaction of a rocket exhaust plume with a particulate-laden surface creates a complex, multiphase flow field that can destabilize the vehicle and damage nearby equipment. This study investigates two methods for capturing the particulate dynamics of plume-surface interaction (PSI): optical fiber-based multi-resolution Mie scattering and multi-dimensional X-ray radiography. Mie scattering was used to track PSI-interacted particles, trace their paths, and measure velocities. While effective for the jet periphery and early PSI stages, the technique becomes limited as the scattering cross-section increases over time due to particle displacement from the soil bed, causing the core to become optically dense and appear as a luminous, opaque region. To address this, X-ray radiography was explored as a complementary method for visualizing the optically dense core. PSI experiments were conducted with both reacting and non-reacting jets to evaluate these approaches across a range of optical and flow parameters. The results demonstrated the capability of the fiber-based multi-resolution imaging system to capture simultaneous fields of view at varying magnifications (1x, 2x, 4x), and the ability of X-ray imaging to penetrate the optically dense plume, revealing flow structures that would otherwise be obscured in scattering-based methods. data were collected for various PSI parameters, including three different heights above the surface, to analyze the ejecta properties and the plume’s temporal evolution. These results provide the first imaging strategy capable of resolving flow structures over a wide spatial dynamic range while also offering the first visualization of the optically dense core. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： X ray radiography

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Directed Illumination of Sunlight Collimated and Observed Beneath a Lunar Lander (DISCOBaLL): Structured Illumination For a Lunar Surface Photogrammetry System

Directed Illumination of Sunlight Collimated and Observed Be...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Eshleman, W. Callahan Tyrrell, Olivia K. Weisberger, Joshua M. Walker, Josiah Z. Danehy, Paul M. Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA23681 United States Department of Mechanical and Aerospace Engineering North Carolina State University RaleighNC United States College of Integrated Science & Engineering James Madison University HarrisonburgVA United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

A lighting system has been developed to provide structured illumination allowing pho togrammetry to be performed during and after landing on extraterrestrial bodies. The system, known as Directed Illumination of Sunlight Collimated and Observed Beneath a Lunar Lander (DISCOBaLL), provides patterned lighting suitable for two- and multiple-camera photogram metry, allowing several different measurements to be obtained including pre-landing terrain shape, visualization and localization of the ejecta sheet during landing, and post-landing terrain shape enabling quantitative measurement of plume-induced cratering. The paper explains the methodology of designing the DISCOBaLL, describes multiple prototypes, and shows the performance of these prototypes using actual solar radiation in a laboratory setting. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Lunar landing

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Frequency-scanning burst-mode filtered Rayleigh scattering for kHz-rate, multi-parameter, gas-phase measurements

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Optics Letters 2025年第3期50卷 912-915页

作者： Braun, Amanda M. Rodrigues, Neil S. Danehy, Paul M. Suppiah, Alexander R. Braun, James Slipchenko, Mikhail N. Meyer, Terrence R. Purdue University School of Mechanical Engineering West LafayetteIN47907 United States NASA Langley Research Center HamptonVA26381 United States Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA26381 United States North Carolina State University RaleighNC27695 United States Spectral Energies LLC 4065 Executive Drive BeavercreekOH45430 United States

Molecular Rayleigh scattering (RS) is sensitive to the pressure, temperature, velocity, and number density of the gaseous flow. Filtered Rayleigh scattering (FRS) utilizes a narrowband molecular filter to remove stray scattering and deconvolve the effect of flow conditions on the signal intensity. As single-frequency, intensity-based FRS techniques can typically only deconvolve a single parameter per detector angle, frequency-scanning (FS) FRS has been used to semi-spectrally resolve the signal and quantify multiple parameters using a single detector. In this work, the FS-FRS data rate was increased by a factor of 105 using a rapid wavelength-tunable burst-mode laser operated at 20 kHz. The technique is demonstrated for simultaneous, spatially resolved temperature, pressure, and radial velocity measurements time-averaged across 1 ms in an underexpanded jet, yielding a measurement rate of 1 kHz for potential use in high-speed flow test facilities. © 2025 Optica Publishing Group. All rights, including for text and data mining (TDM), Artificial Intelligence (AI) training, and similar technologies, are reserved.

关键词： Velocity measurement

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Focused Laser Differential Interferometry: Recent Developments and Applications for Flow measurements

Focused Laser Differential Interferometry: Recent Developmen...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Benitez, Elizabeth K. Ceruzzi, Andrew P. Gragston, Mark Parziale, Nicholaus J. Schmidt, Bryan E. Weisberger, Joshua M. High-Speed Aerodynamics Branch U.S. Air Force Research Laboratory Wright-Patterson AFB OH45433 United States Department of Engineering Science Oxford Thermofluids Institute University of Oxford OxfordOX2 0ES United Kingdom The University of Tennessee-Knoxville KnoxvilleTN37996 United States Stevens Institute of Technology HobokenNJ07030 United States Case Western Reserve University ClevelandOH44106 United States Advanced Measurements and Data Systems Branch NASA Langley Research Center HamptonVA23681 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

Focused laser differential interferometry (FLDI), first introduced in the 1970s, has developed into a powerful tool for the analysis of turbulent dynamics and fluctuations in fluid flows ranging from subsonic to hypersonic. This paper provides a review of recent FLDI developments and applications, including discussions on the basic theory of the instrument, various forms of FLDI, multi-point techniques, utilization in fluid flow measurements, quantitative measurement capabilities, and more. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Laser interferometry

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