Translating Phased Array Measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

Cluts, Jordan D.; Bridges, Jackie; Podboy, Gary G.

doi:10.2514/6.2019-0251

Cited by 5 publications

References 7 publications

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Variable Noise Reduction Systems for a Notional Supersonic Business Jet

Berton

2023

Journal of Aircraft

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A variable noise reduction system consists of equipment on board an airplane that is designed to reduce noise in the vicinity of airports. They are anticipated to be used on supersonic civil aircraft currently under development by industry. They are investigated in this paper for a notional 55,000 kg supersonic business jet. The airplane concept was developed by NASA for use in environmental impact studies conducted by the International Civil Aviation Organization. The variable noise reduction system investigated implements a programmed thrust lapse procedure and a programmed flap retraction procedure. The procedures are expected to reduce noise in aircraft certification as well as in operational practice. Behavior of the aircraft in a noise certification setting is considered. Variables of the procedures are optimized to reduce noise levels. The optimization results in a reduction of 5.2 decibels (in the cumulative effective perceived noise level, measured in EPNdB) relative to levels reported previously. Certification considerations unique to these systems are discussed for transport-category large airplanes and jet-powered airplanes. A novel method for evaluating lateral noise is used.

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Variable Noise Reduction Systems for a Notional Supersonic Business Jet

Berton

2023

Journal of Aircraft

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PIV measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

Bridges

Wernet

2019

AIAA Scitech 2019 Forum

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A model-scale exhaust system was tested to validate low-noise propulsion concepts and noise prediction methods. The tests, referred to as the Top-Mounted Propulsion 2017 (TMP17) tests, involved far-field acoustics, phased array, and particle image velocimetry (PIV). This paper covers the particle image velocimetry portion. Data were acquired at NASA Glenn's Aero-Acoustic Propulsion Lab for a series of nozzles with different chevron designs, both uninstalled and installed on a representative aircraft planform. The impact of the various chevron treatments on the turbulent velocity field was documented, along with the impact of the pylon and planform. When correlated with far-field acoustic measurements and phased array measurements, reported in companion papers, the explanation of acoustic benefits from top-mounted propulsion is clear, as is the path toward optimization of the concept. Nomenclature c speed of sound IVP Inverted Velocity Profile M Mach number NPR nozzle total pressure ratio NTR nozzle total temperature ratio T temperature TKE turbulent kinetic energy TMP17 Top-Mounted Propulsion test 2017 u, v, w jet velocity components U = ⟨u⟩ x axial coordinate Subscripts p, f primary, fan streams j jet exit mix fully mixed ∞ ambient Other ⟨•⟩ average of •

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Noise measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

Bridges

2019

AIAA Scitech 2019 Forum

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A model-scale exhaust system was tested to validate low-noise concepts and noise prediction methods. The tests acquired far-field acoustics, acoustic source distributions, and turbulent velocity statistics; this report covers the far-field acoustic measurements. Data were acquired for a series of nozzles with different chevron designs, both uninstalled and installed on a representative aircraft planform. The impact of the various chevron treatments on the far-field noise was documented, along with the impact of the pylon and planform. For the baseline nozzle, installation produced a 2EPNdB reduction, as was assumed in system studies. Chevrons were used to shift noise sources upstream to maximize the installation benefits and to reduce unshielded sources downstream. These resulted in reductions of 4-5EPNdB relative to the uninstalled baseline nozzle. Detailed analysis of spectral directivities behind the integrated EPNL metric gave insight into how well these concepts actually work. When correlated with particle image velocimetry measurements and phased array measurements, reported in companion papers, the explanation of acoustic benefits from top-mounted propulsion is clear, as is the path toward optimization of the concept. NomenclatureEPNL Effective Perceived Noise Level IVP Inverted Velocity Profile M∞ flight Mach number NPRp nozzle pressure ratio of primary stream NPRf nozzle pressure ratio of fan streams PSD power spectral density of sound pressure

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Translating Phased Array Measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

Cited by 5 publications

References 7 publications

Variable Noise Reduction Systems for a Notional Supersonic Business Jet

Variable Noise Reduction Systems for a Notional Supersonic Business Jet

PIV measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

Noise measurements of a low-noise top-mounted propulsion installation for a supersonic airliner

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