Comparison of holography, beamforming, and intensity-based inverse measurements on full-scale jet noise sources. Part I: Numerical investigations

2015 ◽  
Vol 138 (3) ◽  
pp. 1917-1917
Author(s):  
Alan T. Wall ◽  
Blaine M. Harker ◽  
Trevor A. Stout ◽  
Tracianne B. Neilsen ◽  
Kent L. Gee
Keyword(s):  
Jet Noise ◽  
Full Scale ◽  
Noise Sources ◽  
Numerical Investigations

scholarly journals Data Quality Assurance for Supersonic Jet Noise Measurements

2010 ◽  
Author(s):  
Clifford Brown ◽  
Brenda Henderson ◽  
James Bridges
Keyword(s):  
Data Quality ◽  
High Speed ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Full Scale ◽  
Primary Concern ◽  
Noise Sources ◽  
Supersonic Jet Noise ◽  
Noise Data ◽  
The Impact

The noise created by a supersonic aircraft is a primary concern in the design of future high-speed planes. The jet noise reduction technologies required on these aircraft will be developed using scale-models mounted to experimental jet rigs designed to simulate the exhaust gases from a full-scale jet engine. The jet noise data collected in these experiments must accurately predict the noise levels produced by the full-scale hardware in order to be a useful development tool. A methodology has been adopted at the NASA Glenn Research Center’s Aero-Acoustic Propulsion Laboratory to insure the quality of the supersonic jet noise data acquired from the facility’s High Flow Jet Exit Rig so that it can be used to develop future nozzle technologies that reduce supersonic jet noise. The methodology relies on mitigating extraneous noise sources, examining the impact of measurement location on the acoustic results, and investigating the facility independence of the measurements. The methodology is documented here as a basis for validating future improvements and its limitations are noted so that they do not affect the data analysis. Maintaining a high quality jet noise laboratory is an ongoing process. By carefully examining the data produced and continually following this methodology, data quality can be maintained and improved over time.

Comparison of holography, beamforming, and intensity-based inverse measurements on full-scale jet noise sources. Part II: Experimental results

2015 ◽  
Vol 138 (3) ◽  
pp. 1917-1917
Author(s):  
Blaine M. Harker ◽  
Alan T. Wall ◽  
Trevor A. Stout ◽  
Tracianne B. Neilsen ◽  
Kent L. Gee ◽  
...  
Keyword(s):  
Jet Noise ◽  
Full Scale ◽  
Experimental Results ◽  
Noise Sources

Partial-field decomposition analysis of full-scale supersonic jet noise using optimized-location virtual references

2018 ◽  
Vol 144 (3) ◽  
pp. 1356-1367 ◽  
Author(s):  
Alan T. Wall ◽  
Kent L. Gee ◽  
Kevin M. Leete ◽  
Tracianne B. Neilsen ◽  
Trevor A. Stout ◽  
...  
Keyword(s):  
Supersonic Jet ◽  
Decomposition Analysis ◽  
Jet Noise ◽  
Full Scale ◽  
Supersonic Jet Noise

scholarly journals Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

2012 ◽  
Author(s):  
Gary G. Podboy
Keyword(s):  
Source Localization ◽  
Phased Array ◽  
Noise Source ◽  
Jet Noise ◽  
Companion Paper ◽  
Far Field ◽  
Sound Waves ◽  
Axial Distribution ◽  
Noise Sources ◽  
Interaction Test

An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

Source characterization of full-scale jet noise using vector intensity

2015 ◽  
Vol 138 (3) ◽  
pp. 1916-1916
Author(s):  
Trevor A. Stout ◽  
Kent L. Gee ◽  
Tracianne B. Neilsen ◽  
Alan T. Wall ◽  
Michael M. James
Keyword(s):  
Jet Noise ◽  
Full Scale ◽  
Source Characterization

Designing Clean Jet-Noise Facilities and Making Accurate Jet-Noise Measurements

2003 ◽  
Vol 2 (3) ◽  
pp. 371-412 ◽  
Author(s):  
K. K. Ahuja
Keyword(s):  
Frequency Response ◽  
Internal Noise ◽  
Jet Noise ◽  
Noise Spectrum ◽  
Full Scale ◽  
Research Facility ◽  
High Quality ◽  
Jet Engine ◽  
Noise Measurements ◽  
Noise Data

The main objective of this paper is to provide guidelines for designing and calibrating a high quality, static, jet-noise research facility and making high-quality jet noise measurements. Particular emphasis is placed on methodology for determining if internal noise is dominant in the jet noise spectrum. A section of this document is devoted to clarifying the terminology associated with microphone frequency response corrections and providing a step-wise description of other corrections that must be applied to the measured raw spectra before the jet noise data can be considered accurate and ready for use for extrapolation to full-scale jet engine noise.

scholarly journals Full-Scale Turbofan Demonstration of a Deployable Engine Air-Brake for Drag Management Applications1

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Parthiv N. Shah ◽  
Gordon Pfeiffer ◽  
Rory Davis ◽  
Thomas Hartley ◽  
Zoltán Spakovszky
Keyword(s):  
Passive Control ◽  
Radial Pressure ◽  
Full Scale ◽  
Noise Sources ◽  
Fuel Burn ◽  
Business Jet ◽  
Readiness Level ◽  
Deployable Mechanism ◽  
Swirl Vane ◽  
Aircraft Application

This paper presents the design and full-scale ground-test demonstration of an engine air-brake (EAB) nozzle that uses a deployable swirl vane mechanism to switch the operation of a turbofan's exhaust stream from thrust generation to drag generation during the approach and/or descent phase of flight. The EAB generates a swirling outflow from the turbofan exhaust nozzle, allowing an aircraft to generate equivalent drag in the form of thrust reduction at a fixed fan rotor speed. The drag generated by the swirling exhaust flow is sustained by the strong radial pressure gradient created by the EAB swirl vanes. Such drag-on-demand is an enabler to operational benefits such as slower, steeper, and/or aeroacoustically cleaner flight on approach, addressing the aviation community's need for active and passive control of aeroacoustic noise sources and access to confined airports. Using NASA's technology readiness level (TRL) definitions, the EAB technology has been matured to a level of six, i.e., a fully functional prototype. The TRL-maturation effort involved design, fabrication, assembly, and ground-testing of the EAB's deployable mechanism on a full-scale, mixed-exhaust, medium-bypass-ratio business jet engine (Williams International FJ44-4A) operating at the upper end of typical approach throttle settings. The final prototype design satisfied a set of critical technology demonstration requirements that included (1) aerodynamic equivalent drag production equal to 15% of nominal thrust in a high-powered approach throttle setting (called dirty approach), (2) excess nozzle flow capacity and fuel burn reduction in the fully deployed configuration, (3) acceptable engine operability during dynamic deployment and stowing, (4) deployment time of 3–5 s, (5) stowing time under 0.5 s, and (6) packaging of the mechanism within a notional engine cowl. For a typical twin-jet aircraft application, a constant-speed, steep approach analysis suggests that the EAB drag could be used without additional external airframe drag to increase the conventional glideslope from 3 deg to 4.3 deg, with about 3 dB noise reduction at a fixed observer location.

scholarly journals Full-Scale Turbofan Demonstration of a Deployable Engine Air-Brake for Drag Management Applications

2016 ◽  
Author(s):  
Parthiv N. Shah ◽  
Gordon Pfeiffer ◽  
Rory Davis ◽  
Thomas Hartley ◽  
Zoltán Spakovszky
Keyword(s):  
Passive Control ◽  
Radial Pressure ◽  
Full Scale ◽  
Noise Sources ◽  
Fuel Burn ◽  
Business Jet ◽  
Readiness Level ◽  
Deployable Mechanism ◽  
Swirl Vane ◽  
Aircraft Application

This paper presents the design and full-scale ground-test demonstration of an engine air-brake (EAB) nozzle that uses a deployable swirl vane mechanism to switch the operation of a turbofan’s exhaust stream from thrust generation to drag generation during the approach and/or descent phase of flight. The EAB generates a swirling outflow from the turbofan exhaust nozzle, allowing an aircraft to generate equivalent drag in the form of thrust reduction at a fixed fan rotor speed. The drag generated by the swirling exhaust flow is sustained by the strong radial pressure gradient created by the EAB swirl vanes. Such drag-on-demand is an enabler to operational benefits such as slower, steeper, and/or aeroacoustically cleaner flight on approach, addressing the aviation community’s need for active and passive control of aeroacoustic noise sources and access to confined airports. Using NASA’s Technology Readiness Level (TRL) definitions, the EAB technology has been matured to a level of 6, i.e., a fully functional prototype. The TRL-maturation effort involved design, fabrication, assembly, and ground-testing of the EAB’s deployable mechanism on a full-scale, mixed-exhaust, medium-bypass-ratio business jet engine (Williams International FJ44-4A) operating at the upper end of typical approach throttle settings. The final prototype design satisfied a set of critical technology demonstration requirements that included (1) aerodynamic equivalent drag production equal to 15% of nominal gross thrust in a high-powered approach throttle setting (called dirty approach), (2) excess nozzle flow capacity and fuel burn reduction in the fully deployed configuration, (3) acceptable engine operability during dynamic deployment and stowing, (4) deployment time of 3–5 seconds, (5) stowing time under 0.5 second, and (6) packaging of the mechanism within a notional engine cowl. For a typical twin-jet aircraft application, a constant-speed, steep approach analysis suggests that the EAB drag could be used without additional external airframe drag to increase the conventional glideslope from 3 to 4.3 degrees, with about 3 dB noise reduction at a fixed observer location.

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