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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

Quiet Supersonic Flights 2018 (QSF18) Test: Galveston, Texas Risk Reduction for Future Community Testing with a Low-Boom Flight Demonstration Vehicle

The Quiet Supersonic Flights 2018 (QSF18) Program was designed to develop tools and methods for demonstration of overland supersonic flight with an acceptable sonic boom, and collect a large dataset of responses from a representative sample of the population. Phase 1 provided the basis for a low amplitude sonic boom testing in six different climate regions that will enable international regulatory agencies to draft a noise-based standard for certifying civilian supersonic overland flight. Phase 2 successfully executed a large scale test in Galveston, Texas, developed well documented data sets, calculated dose response relationships, yielded lessons, and identified future risk reduction activities.

Galveston↗
NASA NTRS2020

Quiet Supersonic Flights 2018 (QSF18) Test: Galveston, Texas Risk Reduction for Future Community Testing with a Low-Boom Flight Demonstration Vehicle

The Quiet Supersonic Flights 2018 (QSF18) Program was designed to develop tools and methods for demonstration of overland supersonic flight with an acceptable sonic boom, and collect a large dataset of responses from a representative sample of the population. Phase 1 provided the basis for a low amplitude sonic boom testing in six different climate regions that will enable international regulatory agencies to draft a noise-based standard for certifying civilian supersonic overland flight. Phase 2 successfully executed a large scale test in Galveston, Texas, developed well documented data sets, calculated dose response relationships, yielded lessons, and identified future risk reduction activities.

Galveston↗
NASA NTRSDate not supplied

An Overview of NASA's Low Boom Flight Demonstration

NASA will soon begin a series of tests that will collect nationally representative data on how people perceive low noise supersonic overflights. For half a century, civilian aircraft have been required to fly slower than the speed of sound over land to prevent “creating an unacceptable situation” on the ground due to sonic booms. However, new aircraft shaping techniques have led to dramatic changes in how shockwaves from supersonic flight merge together as they travel to the ground. What used to sound like a boom on the ground will be transformed into a thump. NASA is now building a full-scale, piloted demonstration aircraft called the X-59 to demonstrate low noise supersonic flight. In 2024, the X-59 aircraft will commence a national series of community overflight tests to collect data on how people perceive “sonic thumps.” The community response data will be provided to national and international noise regulators as they consider creating new standards that allow supersonic flight over land at acceptably low noise levels.

Sonic Boom↗
NASA NTRS1999

Low-Boom SR-71 Modified Signature Demonstration Program

A flight program using the SR-71 airplane to validate sonic boom technologies for High-Speed Commercial Transport (HSCT) operation and potentially for low- or softened-boom design configurations is described. This program employs a shaped signature modification to the SR-71 airplane which is designed to demonstrate computational fluid dynamics (CFD) design technology at a full-scale HSCT operating condition of Mach 1.8 at 48,000 feet altitude. Test plans call for measurements in the near-field, at intermediate propagation altitudes, and through the more turbulent boundary layer near the Earth surface. The shaped signature modification to the airplane is comprised of added cross-section areas on the underside of the airplane forward of the wing and engine nacelles. Because the flight demonstration does not approach maximum SR-71 altitude or Mach number, the airplane provides more than adequate performance and maneuver margins for safe operation of the modified airplane. Probe airplane measurements in the near-field will use fast response pressure sensors. Far-field and ground-based boom measurements will use high response microphones or conventional sonic boom field recorders. Scope of the planned demonstration flights also includes ground level measurements during conditions which cause minimal signature distortion and conditions which cause high distortion of the signature.

David Lux↗
NASA NTRSDate not supplied

The effect of modeling dose uncertainty on low-boom community noise dose-response curves

In logistic dose-response modeling, failing to account for uncertainty in estimated doses can cause an artificial flattening or attenuation of the slope of the summary curve. In Lee et al. [J. Acoust. Soc. Am. 147(4), pp. 2222-2234 (2020)], data from two NASA low-amplitude sonic boom community noise survey tests were modeled using a Bayesian multilevel logistic regression (MLR) statistical model that assumed there was no uncertainty in the noise dose estimates. However, in these community tests, the noise dose uncertainty was estimated by Page et al. [NASA/CR-2014-218180 and NASA/CR-2020-220589/Volume I] using a leave-one-out method. In the current work, a term was added to extend the Bayesian MLR model to account for the estimated noise dose uncertainty quantified in the Page et al. analyses. This uncertainty term was included in two ways, either as classical or as Berkson uncertainty, and yield similar results. When the uncertainty is accounted for in the Bayesian MLR model, the dose-response curves become 5-10% steeper, but the difference in the noise dose that elicits a 5% highly annoyed response is small (less than 1 dB). This result is encouraging for future X-59 community tests whose survey area will be sparsely populated with noise monitors.

X-59↗
NASA NTRS1992

Assessment and design of low boom configurations for supersonic transport aircraft

A review is presented of presently utilized sonic boom prediction and minimization techniques. The three-pronged approach - acceptability studies, atmospheric propagation studies, and configuration design and operation, to the sonic boom problem as an element of the High Speed Research Program are discussed. Experimental and theoretical results of concepts designed to validate present minimization methods are given.

Darden, Christine M.↗
NASA NTRS2011

USM3D Analysis of Low Boom Configuration

In the past few years considerable improvement was made in NASA's in house boom prediction capability. As part of this improved capability, the USM3D Navier-Stokes flow solver, when combined with a suitable unstructured grid, went from accurately predicting boom signatures at 1 body length to 10 body lengths. Since that time, the research emphasis has shifted from analysis to the design of supersonic configurations with boom signature mitigation In order to design an aircraft, the techniques for accurately predicting boom and drag need to be determined. This paper compares CFD results with the wind tunnel experimental results conducted on a Gulfstream reduced boom and drag configuration. Two different wind-tunnel models were designed and tested for drag and boom data. The goal of this study was to assess USM3D capability for predicting both boom and drag characteristics. Overall, USM3D coupled with a grid that was sheared and stretched was able to reasonably predict boom signature. The computational drag polar matched the experimental results for a lift coefficient above 0.1 despite some mismatch in the predicted lift-curve slope.

Carter, Melissa B.↗
NASA NTRS2019

Jet Noise Prediction for Low Boom Aircraft

Enabling jet acoustics simulations on full scale flight vehicles utilizing zonal hybrid RANS/LES within the Launch Ascent and Vehicle Aerodynamics (LAVA) Solver. Hybrid RANS/LES technology will assist in the development for innovative concepts for integrated supersonic propulsion systems. Modeling and simulation practices must be scrutinized further and new methods need to be developed.

Stich, Gerrit↗
NASA NTRS2019

Predicting Jet Noise for Full-Scale Low-Boom Aircraft

Supersonic vehicle research addresses the development of tools, technologies, and knowledge to help eliminate technical barriers to practical commercial supersonic flight. While the major focus of this research has been on reducing the ground signature at supersonic cruise, airplanes must also satisfy noise constraints during takeoff and landing at subsonic speeds, and jet noise is the main sound source. We use computational aeroacoustic sim- ulation tools to assess new designs at these lower speeds. We are further scrutinizing both modeling and simulation practices and the use of hybrid Reynolds-averaged Navier Stokes/Large- Eddy Simulations methods and developing new methods to predict jet noise on a full flight configuration.

Stich, Gerrit-Daniel↗