Quantcast Table 8B Objectives and Key Acoustic Results of Model Studies

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Table 8B
Objectives and Key Acoustic Results of Model Studies -
Western Electro-Acoustic Laboratory Study 1980 [18]
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OBJECTIVES
RESULTS
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Provide Acoustical Performance
date for:
1. In a certain frequency
range lined augmenters of
concentric construction may
1.
Round vs abround augmenters
yield lower sound attenuation
than area-equivalent lined
2.
Turning vanes vs rampabround
augmenters of cross-section.
3.
Ramp modifications
2. Turning vanes generate
substantially more noise than
4.
Coanda suppressor
a lined 45 deg. ramp.  The noise
generated by the turning vanes
can be reduced by a lined stack
extension to levels similar to
those obtained with a lined 45
deg. ramp without a lined stack
extension.
3. The ramp modifications
investigated did not result
in a noticeable reduction of
the net exhaust sound power.
No investigations have been
carried out to determine
whether the modifications
influence far field noise at
typical far field positions
at ground level.
4. Coanda surface turning
provides measurable noise
reduction.
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