Perceived Noise Analysis for Offset Jets Applied to Commercial Supersonic Aircraft

Huff, Dennis L.; Henderson, Brenda S.; Berton, Jeffrey J.; Seidel, Jonathan A.

doi:10.2514/6.2016-1635

Cited by 21 publications

(11 citation statements)

References 2 publications

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“…Although advances have been made in the reduction of jet noise, these have primarily been for transonic and subsonic commercial applications. Renewed interest in supersonic transport vehicles through the Commercial Supersonic Technology project of the Advanced Air Vehicles Program at NASA has prompted research in mitigating jet noise in heated, high speed jet plumes (Huff et al (2016)). Based on the set performance and noise goals of the program, new engine technologies are being researched.…”

Section: Introductionmentioning

confidence: 99%

“…Based on the set performance and noise goals of the program, new engine technologies are being researched. One of the more promising ideas is a variable cycle or adaptive cycle engine which would offer a third exhaust stream, in addition to the bypass and core streams that are already commonplace in aircraft engines (Huff et al (2016)). Recent computational and experimental work has shown that nozzles with a tertiary stream offer a potential for noise reduction (Henderson (2012); Henderson and Leib (2015)).…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of convection velocity and turbulence measurements in three-stream jets

Stuber

Lowe

2019

Exp Fluids

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Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high speed threestream nozzles. A time-resolved Doppler global velocimetry (DGV) instrument was applied in the Nozzle Acoustic Test Rig (NATR) at NASAs Aero-Acoustic Propulsion Lab to measure 250 kHz repetition laser scattering signals arising from seeding particles at 32 points in high speed flow. Particle image velocimetry (PIV) measurements previously reported by NASA provided mean velocity and turbulence intensity. Results for convection velocity of the particle concentration field were obtained from the DGV data for three-stream nozzle configurations using a cross-correlation approach. The three-stream cases included an axisymmetric and an asymmetric, offset nozzle configuration. For the axisymmetric case, areas of high convection velocity and turbulence intensity were found to occur 4 to 6 area-equivalent nozzle diameters downstream from the nozzle exit. Comparison of convection velocity between the axisymmetric and offset cases show this same region as having the greatest reduction in convection velocity due to the offset, up to 20% reduction for the offset case compared to the axisymmetric case. These findings suggest this region along the centerline near the end of the potential core is an important area for noise generation with jets and contributes to the noise reductions seen from three-stream offset nozzles.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis of convection velocity and turbulence measurements in three-stream jets

Stuber

Lowe

2019

Exp Fluids

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“…The International Civil Aviation Organization (ICAO) is enforcing stricter noise regulations (Chapter 4 minus 7 EPNdB, effective December 2017) 2 , requiring innovative airframe configurations and propulsive systems that are both efficient and quiet. A viable engine for supersonic aircraft that meets these criteria may have a variable cycle, where the bypass ratio could be increased to reduce turbulent mixing noise at takeoff, and decreased during supersonic cruise to preserve engine performance 3 . Variable cycle engine technology will be enabled by two-or three-stream nozzle architectures, which would allow implementing noise reduction techniques that utilize the bypass stream.…”

Section: Introductionmentioning

confidence: 99%

“…The secondary nozzle can be tailored to induce asymmetry in the plume, at azimuthal directions where noise reduction is desired. Inducing asymmetry in the plume entails either geometrically offsetting the nozzle ducts 3,13,14 , or installing devices that deflect the bypass stream 13,15,16,17 . The misalignment between the primary and secondary streams produces a thick, lowspeed layer, that is oriented typically at downward and sideline azimuthal directions.…”

Section: Introductionmentioning

confidence: 99%

“…The offset, tertiary stream reduced noise along the thick side of the jet when the core flow is operating at supersonic conditions. Huff et al assessed the capability of three-stream, offset duct configurations to meet Chapter 14 noise regulations 3 . Their results indicated that offsetting the tertiary duct alone would not reduce noise levels below sufficient margin to Chapter 14 (Chapter 4 minus 10 EPNdB).…”

Section: Introductionmentioning

confidence: 99%

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Investigation of Isolated and Installed Three-Stream Jets from Offset Nozzles

Phong

Papamoschou

2017

55th AIAA Aerospace Sciences Meeting

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An experimental aeroacoustic investigation of three-stream nozzle concepts with potential to reduce takeoff noise from future supersonic aircraft is presented. We use guidance from previous three-stream nozzle experiments to explore asymmetric designs where both secondary and tertiary streams are concentrated in the downward direction. The impact of increasing the plug size on noise is examined. Enlarging the plug provides moderate noise reduction for axisymmetric and asymmetric nozzle configurations. Nozzle configurations that combine asymmetry in both secondary and tertiary streams provide a distinct noise benefit in the sideline azimuthal direction. Considering the sound pressure level at a fullscale frequency around 300 Hz, the combined effects of the enlarged plug and dual asymmetry yield reductions of 15 dB and 6 dB in the downward and sideline azimuthal directions, respectively, and at angles close to the angle of peak emission. Installation effects with an aft deck indicate minimal impacts on radiated noise, except in the case of a long deck at a scrubbing position. In that case, the ability of the asymmetric nozzles to reduce noise is disrupted. Marginal shielding at high frequency is noted at forward observer angles.

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