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NASA Technical Reports Server (NTRS) 20130000324: Aeroacoustics of ... |
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by NASA Technical Reports Server (NTRS) |
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Results from acoustic measurements of noise radiated from |
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a heated, three-stream, co-annular exhaust system |
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operated at subsonic conditions are presented. The |
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experiments were conducted for a range of core, bypass, |
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and tertiary stream temperatures and pressures. The |
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nozzle system had a fan-to-core area ratio of 2.92 and a |
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tertiary-to-core area ratio of 0.96. The impact of |
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introducing a third stream on the radiated noise for |
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third-stream velocities below that of the bypass stream |
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was to reduce high frequency noise levels at broadside |
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and peak jet-noise angles. Mid-frequency noise radiation |
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at aft observation angles was impacted by the conditions |
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of the third stream. The core velocity had the greatest |
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impact on peak noise levels and the bypass-to-core mass |
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flow ratio had a slight impact on levels in the peak jet- |
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noise direction. The third-stream jet conditions had no |
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impact on peak noise levels. Introduction of a third jet |
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stream in the presence of a simulated forward-flight |
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stream limits the impact of the third stream on radiated |
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noise. For equivalent ideal thrust conditions, two-stream |
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and three-stream jets can produce similar acoustic |
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spectra although high-frequency noise levels tend to be |
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lower for the three-stream jet. |
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Date Published: 2016-11-12 02:07:25 |
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Identifier: NASA_NTRS_Archive_20130000324 |
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Item Size: 16920821 |
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Language: english |
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Media Type: texts |
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