Results for “sonic” — Page 15

NASA NTRS2016

Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

Wind Tunnel↗

NASA NTRSDate not supplied

USM3D Simulations for Third Sonic Boom Workshop

The NASA USM3D flow solver was used to compute test cases for the Third AIAA Sonic Boom Prediction Workshop (SBPW3). The test cases include an axisymmetric equivalent area body, a near field biconvex shock-plume interaction wind tunnel model, and the C608 Low Boom Flight Demonstrator. Numerical simulations were conducted on the mixed element grids and the tetrahedral grids provided by the workshop committee, as well as a family of grids generated by an in-house approach for sonic boom analyses known as Boom Grid. The near-field pressure signatures were extracted, propagated to the ground and the perceived loudness levels on the ground was computed. The USM3D near-field pressure signatures,corresponding ground signatures, and loudness levels on the ground are compared with mean values from other workshop participants.

Supersonics↗

NASA NTRSDate not supplied

Modelling Sonic Boom Propagation through Planetary Boundary Layer Turbulence near the Lateral Extent of the Carpet

Nonlinear acoustic propagation of sonic booms in the atmospheric boundary layer is considered in the context of a one-way solution to a third order wave equation. A split-step approach is utilized to compute different physical effects efficiently. Unlike previous approaches, the diffraction effects are computed exactly in the forward direction with no restriction on the angle of propagation. This results in more accurate modelling of sonic boom near the carpet edge. Heterogenous flow effects are incorporated with a wide-angle parabolic approximation. Nonlinear propagation is computed with a Burgers-Hayes method. Turbulence in the medium is constructed by the method of random Fourier modes. The turbulence spectra are constructed using an altitude dependent 3-dimensional von Karman spectrum. The turbulence field is considered frozen, as the eddy turnover time in the atmospheric boundary layer is generally much larger than the propagation time of the acoustic wave. Comparisons with benchmark predictions from the PCBoom software are conducted. The benchmark cases provide insight into the accuracy of the current prediction code for non-turbulent atmospheres. Future work is discussed regarding the prediction of shaped booms, boundary conditions, and predictions near the lateral extent of the boom carpet where previous approaches fail to capture the diffraction effects.

sonic boom↗

NASA NTRSDate not supplied

Nearfield Anisotropic Mesh Adaptation for the Third AIAA Sonic Boom Workshop

Sonic boom prediction is critical for the development of low-boom supersonic aircraft and encouraging a replacement of the overland commercial supersonic ban with a certification standard. The Third AIAA Sonic Boom Workshop nearfield test cases provide a unique opportunity to review anisotropic adaptive-mesh strategies for complex geometries with important propulsion interaction effects. Anisotropic metrics formulated to control estimated Mach interpolation and integrated nearfield pressure signature (goal-oriented) errors are compared with the results obtained on workshop-provided meshes. Detailed flow solutions and mesh renderings are combined with computational schlieren images to reveal the complex interactions present in a shock-plume interaction wind tunnel model and a prototype of the Low-Boom Flight Demonstrator. A favorable comparison of independent implementations of the entire simulation process provides evidence that each process is implemented correctly and sets a solid foundation for confidence in the nearfield prediction of each method.

sonic boom↗

NASA NTRSDate not supplied

USM3D Simulations for Third Sonic Boom Workshop

The NASA USM3D flow solver was used to compute test cases for the Third AIAA Sonic Boom Prediction Workshop (SBPW3). The test cases include a nearfield biconvex shock-plume interaction wind tunnel model, and the C608 Low Boom Flight Demonstrator. Numerical simulations were conducted on the mixed-element and tetrahedral grids provided by the workshop committee, as well as a family of grids generated by an in-house approach for sonic boom analyses known as BoomGrid. The near-field pressure signatures were extracted, propagated to the ground and the perceived loudness levels on the ground were computed. The USM3D near-field pressure signatures, corresponding ground signatures, and loudness levels on the ground are compared with that of mean values from other workshop participants. The effect of three flux-limiters on the accuracy of near-field pressure signatures prediction was investigated and results are compared with that of mean values from other workshop participants. The effect of using wall function grids in accurately predicting near-field pressure signatures was also evaluated.

Supersonics↗

NASA NTRSDate not supplied

USM3D Simulations for the Third Sonic Boom Prediction Workshop (SBPW-3)

The NASA USM3D flow solver was used to compute test cases for the Third AIAA Sonic Boom Prediction Workshop (SBPW3). The test cases include a nearfield biconvex shock-plume interaction wind tunnel model, and the C608 Low Boom Flight Demonstrator. Numerical simulations were conducted on the mixed-element and tetrahedral grids provided by the workshop committee, as well as a family of grids generated by an in-house approach for sonic boom analyses known as BoomGrid. The near-field pressure signatures were extracted, propagated to the ground and the perceived loudness levels on the ground were computed. The USM3D near-field pressure signatures, corresponding ground signatures, and loudness levels on the ground are compared with that of mean values from other workshop participants. The effect of three flux-limiters on the accuracy of near-field pressure signatures prediction was investigated and results are compared with that of mean values from other workshop participants. The effect of using wall function grids in accurately predicting near-field pressure signatures was also evaluated.

Supersonics↗

NASA NTRS2023

Multiple Scattering Theory for Modeling Sonic Booms in Atmospheric Turbulence

Sonic booms are often modeled using Burgers equations accounting for dominant propagation effects. Scattering effects of turbulence, however, have not been incorporated into such equations, although these effects are ubiquitous in measured sonic booms. This paper formulates the mean scattering effects, including backscattering, using multiple scattering theory and ensemble averaging. It obtains an acousto-turbulence interaction energy representing the interaction of an acoustic wave field with a turbulence field. The interaction energy gives rise to a scattering wavenumber, a complex-valued correction to the free-space wavenumber. The scattering wavenumber leads to a dispersion and attenuation of the mean waveform due to backscattering, and can be obtained from a derived exact solution. An existing Burgers equation is extended to include the scattering effects of turbulence as an additional linear term. Numerical simulations of an N-wave and a low boom show that the mean scattering effects lead to shock thickening in the mean waveforms as well as reduce the peak amplitudes and total energy contents. The energy reduction is less severe in the low boom than in the N-wave and is dependent on the variance, correlation length, and thickness of the turbulence field.

sonic booms↗

NASA NTRS2022

X-59 Sonic Boom Test Results from the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel

A wind tunnel test was conducted to investigate near-field sonic boom pressure signatures from a model of the X-59 Low-Boom Flight Demonstrator aircraft. A 1.62%-scale model of the aircraft in the C612A configuration was fabricated for the wind tunnel test, which took place in the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel in September and October 2021. The model had provisions for two different mounting options: a swept blade strut that attached at the top of model ahead of the inlet, and rear-entry sting that was made as one piece with a dummy nacelle, and which had a 2”-long cylindrical segment aft of the nozzle exit before tapering up in size. The blade strut allowed for a clean aft end of the model for evaluation of the shocks from that region, while the sting avoided the significant distortions of the flow and shocks from the blade strut along the top of the model. Both the sting and the strut had adapters that attached to a force balance. The model had alternate parts for ±0.5° deflections of the flaps, ailerons, and stabilator, and ±1° deflections of the T-tail horizontal surface. Off-body static pressure measurements of the flow field below the model were made by use of a pressure rail which had 420 orifices along its tip. The model was positioned at various heights from the rail by vertical movement of the wind tunnel strut, and at various longitudinal stations relative to the rail by means of a linear actuator mounted between the tunnel strut and the balance. The longitudinal positioning allowed multiple pressure signatures to be obtained along different portions of the rail. These signatures were aligned by accounting for the model longitudinal movement and then averaged to take out the effects of tunnel flow distortions and the interference of the rail flow field and shocks on the model pressure signatures. The test was run at approximate Mach numbers of 1.36, 1.4, and 1.47, and the model was set at various angles of attack and roll relative to the rail. Plots of the model signatures for all the variations of Mach number, model angles, control deflections, and height relative to the rail are provided throughout the report. Repeatability was generally very good and gave confidence in the quality of the measurements. The signatures measured at various heights from the rail provided insight into the aging of the model shocks as they propagated from 1.2 to 3 body lengths from the model. Off-track signatures up to 45° from centerline obtained by rolling the model gave indications of the shock flow fields across the width of the sonic boom carpet. The deflections of the various control surfaces allowed assessment of the boom sensitivity to the control surface movements.

Sonic boom↗

NASA NTRS2023

X-59 Sonic Boom Test Results from the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel

A wind tunnel test was conducted to investigate near-field sonic boom pressure signatures of the X-59 Low-Boom Flight Demonstrator aircraft. A 1.62%-scale model of the aircraft was fabricated for the wind tunnel test, which took place in the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel in September and October 2021. The model had provisions for being mounted by a swept blade strut that attached at top of model ahead of the inlet, or by a rear-entry sting that held the model at the location of the nacelle. The model had alternate parts for ±0.5° deflections of the flaps, ailerons, and stabilator, and ±1° deflections of the T-tail. Off-body static pressure measurements of the flow field below the model were made on a pressure rail which had 420 orifices along its tip. The model was positioned at various heights from the rail by vertical movement of the tunnel strut, and at various longitudinal stations relative to the rail by means of a linear actuator mounted between the wind tunnel strut and the balance. Spatial averaging of model pressure signatures acquired over a range of longitudinal positions reduced the effects of tunnel flow distortions and the interference of the rail flow field and shocks on the model pressure signatures. The test was run at approximate Mach numbers of 1.36, 1.4, and 1.47, and the model was set at various angles of attack and roll relative to the rail. Plots of the model signatures for representative variations of Mach number, model angles, control deflections, and height relative to the rail are provided throughout the report. Repeatability was generally very good and gave confidence in the quality of the measurements. The signatures measured at various heights from the rail provided insight into the aging of the model shocks as they propagated from 1.2 to 3 body lengths from the model. Off-track signatures up to 45° from centerline obtained by rolling the model gave indications of the shock flow fields across the width of the sonic boom carpet. The deflections of the various control surfaces allowed assessment of the boom sensitivity to the control surface movements.

Sonic boom↗

NASA NTRSDate not supplied

Toward High-Quality X-59 Sonic Thump Measurements

Brigham Young University has been investigating best practices for recommendation to NASA in upcoming X-59 sonic thump measurements. This preparatory work has focused both on obtaining high-fidelity data and standardizing signal analysis techniques for sonic thumps. Included in the research are topics such as whether to use a ground-based or elevated microphone, how to use low-noise microphones and still recover high-fidelity data at low frequencies, and estimating the uncertainty in a given measurement due to local atmospheric turbulence effects. Also included is a study of windowing techniques, zero padding, and the removal of high-frequency ambient noise contamination.

sonic boom↗

NASA NTRS2023

X-59 Sonic Boom Test Results from the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel

A wind tunnel test was conducted to investigate near-field sonic boom pressure signatures of the X-59 Low-Boom Flight Demonstrator aircraft. A 1.62%-scale model of the aircraft was fabricated for the wind tunnel test, which took place in the NASA Glenn 8- by 6-Foot Supersonic Wind Tunnel in September and October 2021. The model had provisions for being mounted by a swept blade strut that attached at top of model ahead of the inlet, or by a rear-entry sting that held the model at the location of the nacelle. The model had alternate parts for ±0.5° deflections of the flaps, ailerons, and stabilator, and ±1° deflections of the T-tail. Off-body static pressure measurements of the flow field below the model were made on a pressure rail which had 420 orifices along its tip. The model was positioned at various heights from the rail by vertical movement of the tunnel strut, and at various longitudinal stations relative to the rail by means of a linear actuator mounted between the wind tunnel strut and the balance. Spatial averaging of model pressure signatures acquired over a range of longitudinal positions reduced the effects of tunnel flow distortions and the interference of the rail flow field and shocks on the model pressure signatures. The test was run at approximate Mach numbers of 1.36, 1.4, and 1.47, and the model was set at various angles of attack and roll relative to the rail. Plots of the model signatures for representative variations of Mach number, model angles, control deflections, and height relative to the rail are provided throughout the report. Repeatability was generally very good and gave confidence in the quality of the measurements. The signatures measured at various heights from the rail provided insight into the aging of the model shocks as they propagated from 1.2 to 3 body lengths from the model. Off-track signatures up to 45° from centerline obtained by rolling the model gave indications of the shock flow fields across the width of the sonic boom carpet. The deflections of the various control surfaces allowed assessment of the boom sensitivity to the control surface movements.

Sonic boom↗

NASA NTRS2024

Sonic Boom Analyses in Support of Improved X-59 Community Noise Testing

informing measurement planning and analysis of quiet supersonic aircraft community testing. The report is divided into three main sections: (1) investigations on the impacts of contaminating noise on sonic boom community noise metrics; (2) investigations into sonic boom variability, including turbulence effects on metrics of interest and development of a data-driven boom variability analysis framework; (3) other studies that support developing improved methodologies for community testing and analysis.

community noise↗

NASA NTRS2025

Uncertainty Quantification for Empirical X-59 Sonic Boom Loudness Levels

Estimates of the total uncertainty for empirically determined loudness levels are documented when GRS (Ground Recording System) noise monitors are used to record X 59 sonic boom waveforms. The total uncertainty is characterized by combining nine different sources of uncertainty that may affect the apparent gain of the measurement chain. These uncertainty estimates are presented as expected measurement error relative to the true loudness level, and separate error estimates are provided for eight different noise metrics in which NASA has interest. The behavior of the Perceived Level (PL) metric is studied within the report body, while the total uncertainties for the seven other noise metrics are summarized in appendices for brevity. The effects of four sources of uncertainty are estimated simply from information found on hardware specification sheets provided by the manufacturer. However, mock acoustic recordings are created to estimate the effects of other sources because those effects are expected to induce spectral coloration, so they may vary with noise metric type and sound level. These sources are not well modeled by simple gain adjustments. Importantly, measurement error is computable when processing mock recordings since the true levels are knowable, which is not the case when processing data recorded in the field. Specifically, the true levels are knowable because the components of the mock recordings are separable – e.g., loudness levels of booms can be computed with or without superimposed background noise. Mock acoustic recordings also have the benefit of allowing analysis of sonic booms from vehicles that are not yet flying, like the X-59, since the mock recordings are created by combining vehicle-specific predicted waveforms with other audio sources. The estimates of total measurement error are documented as a function of the signal-to-noise ratio (SNR) of the loudness level, where the corrected SNR is computed while accounting for the effects of the method that is used to correct for background noise contamination when computing the noise metric values. The corrected SNR calculations used here can be applied to both mock recordings and in-field measurements, so the uncertainty of in-field recordings can be found using pre-computed lookup tables that identify the relationship between metric type, corrected SNR, and the expected measurement error.

Sonic Boom↗

DOE OSTI2025

Dissolved Oxygen Redox as the Source of Hydrogen Peroxide and Hydroxyl Radical in Sonicated Emulsive Water Microdroplets

Sonicated emulsive water microdroplets (SEWMs) accelerate and enable a variety of catalyst-free chemical transformations. However, significant unanswered questions remain regarding the chemical intermediates they form and their possible redox origin. In this study, we identified dissolved O 2 as the primary originator of reactive oxygen species (ROS) such as OH• and H 2 O 2. We uncovered the role of dissolved O 2 redox by using a combination of microelectrochemical methods to detect H 2 O 2 , isotopic methods to identify the source of H 2 O 2 , and a combination of electron spin resonance and the DMPO spin trap to detect radicals such as OH•. Notably, we found that H 2 O 2 production is correlated with O 2 content via a reduction pathway enabled by a sufficiently large reducing power that can additionally generate H 2 and even perform Pb electroless deposition on Au and Cu metal substrates. Building on our findings, continuous O 2 bubbling of SEWMs showed accumulation of H 2 O 2 up to ∼88 mM in the aqueous phase within 1 h of sonication, demonstrating the scale-up promise of this method. Distinct to sonochemistry of a single phase, this study advances our understanding of the confluence of redox and chemical reaction mechanisms within SEWMs as a biphasic system. This insight paves the way for improving their reaction kinetics, yield, and selectivity, positioning these attractive redox microreactors as alternatives to traditional electrolyzers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Sonic Lift-off of GaAs-based Solar Cells with Reduced Surface Facets

Spalling has been proposed as a promising kerfless technique for slicing thin wafers and devices, enhancing the wafer yield from an ingot by reducing kerf-losses and enabling substrate reuse for the case of costly devices. The main challenge of spalling is to control the roughness and thickness variation of the spalled wafers that can be as high as 100% of the wafer thickness. Here, we have shown previously that the thickness variations are largely influenced by the interaction of the crack front with its own reflected waves. Herein we show that through Sonic Lift-off we can offer a modification to standard spalling technologies that minimizes the interaction of reflected waves with the crack front during lift-off of GaAs(100)-based solar cells. We show that the average surface facets amplitude can be reduced by 96% while obtaining a high quality bulk with no discernible residual strain as measured by PL. The resulting spalling depth can easily be tuned from 100 µm to less than 15µm. The electrical characterization of the Sonic lift-off cell shows no degradation of the VOC and a power conversion within 99% relative of a non-spalled baseline.

42 ENGINEERING↗

DOE OSTI2025

Site A1 - Sonic Anemometer / Reviewed Data

This dataset contains sonic anemometer data deployed on tethered balloon system at AWAKEN site A1. The sonic data include time stamp, wind speed, wind direction, turbulence, and boom attitude and motion.

17 WIND ENERGY↗

DOE OSTI2025

TTP - WREF 3D Sonic Anemometer Tower D / Raw Data

Tower D is one of four subcanopy towers that were installed in the WREF canopy across a transect distance of 200m. Tower D had one CSAT3-3D sonic mounted at a height of 2.7 m a.g.l. The sonic is facing 290 degrees. The towers were installed to observe flow just above the forest floor and to identify any advection flows in the canopy. These data were also part of a larger ICOS project looking at forest flow coupling/decoupling with tower sites in Italy and Czech Republic.

17 WIND ENERGY↗

DOE OSTI2025

TTP - WREF 3D Sonic Anemometer Tower C / Raw Data

Tower C is one of four subcanopy towers that were installed in the WREF canopy across a transect distance of 200m. Tower C had one CSAT3-3D sonic mounted at a height of 2.7 m a.g.l. The sonic is facing 270 degrees. The towers were installed to observe flow just above the forest floor and to identify any advection flows in the canopy. These data were also part of a larger ICOS project looking at forest flow coupling/decoupling with tower sites in Italy and Czech Republic.

17 WIND ENERGY↗