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

Abstract

Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high-speed three-stream nozzles. Time-resolved flow imaging using a photomultiplier tube array was applied in the Nozzle Acoustic Test Rig 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 measurements previously reported by NASA provided mean velocity and turbulence intensity. Results for convection velocity of the particle concentration field were obtained from the time-resolved 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 4–6 area-equivalent nozzle diameters downstream from the nozzle exit. Comparison of convection velocity between the axisymmetric and offset cases shows 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. Finally, these findings suggest that this region along the centerline near the end of the potential core is an important area for noise generation with jetsmore » and contributes to the noise reductions seen from three-stream offset nozzles.« less

Authors:
 [1]; ORCiD logo [1];  [1]
  1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Advanced Propulsion and Power Lab.
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
US Department of the Navy, Office of Naval Research (ONR); USDOE
OSTI Identifier:
1511241
Report Number(s):
LA-UR-18-28093
Journal ID: ISSN 0723-4864
Grant/Contract Number:  
89233218CNA000001
Resource Type:
Accepted Manuscript
Journal Name:
Experiments in Fluids
Additional Journal Information:
Journal Volume: 60; Journal Issue: 5; Journal ID: ISSN 0723-4864
Publisher:
Springer
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 33 ADVANCED PROPULSION SYSTEMS

Citation Formats

Stuber, Marcie, Lowe, K. Todd, and Ng, Wing F. Synthesis of convection velocity and turbulence measurements in three-stream jets. United States: N. p., 2019. Web. doi:10.1007/s00348-019-2730-5.
Stuber, Marcie, Lowe, K. Todd, & Ng, Wing F. Synthesis of convection velocity and turbulence measurements in three-stream jets. United States. doi:10.1007/s00348-019-2730-5.
Stuber, Marcie, Lowe, K. Todd, and Ng, Wing F. Wed . "Synthesis of convection velocity and turbulence measurements in three-stream jets". United States. doi:10.1007/s00348-019-2730-5.
@article{osti_1511241,
title = {Synthesis of convection velocity and turbulence measurements in three-stream jets},
author = {Stuber, Marcie and Lowe, K. Todd and Ng, Wing F.},
abstractNote = {Key flow regions linked to jet noise sources are investigated through comparison of convection velocity and turbulence measurements in high-speed three-stream nozzles. Time-resolved flow imaging using a photomultiplier tube array was applied in the Nozzle Acoustic Test Rig 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 measurements previously reported by NASA provided mean velocity and turbulence intensity. Results for convection velocity of the particle concentration field were obtained from the time-resolved 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 4–6 area-equivalent nozzle diameters downstream from the nozzle exit. Comparison of convection velocity between the axisymmetric and offset cases shows 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. Finally, these findings suggest that 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.},
doi = {10.1007/s00348-019-2730-5},
journal = {Experiments in Fluids},
number = 5,
volume = 60,
place = {United States},
year = {2019},
month = {4}
}

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This content will become publicly available on April 17, 2020
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