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How to Predict In-flight Coaxial Jet Noise

Posted April 03, 2015 12:00 AM by SavvyExacta
Pathfinder Tags: aerospace ESDU

Did you know that there are regulations regarding aircraft noise? Software is a valuable tool for predicting what aircraft might sound like in certain scenarios.

ESDU software estimates the change in coaxial jet noise spectrum levels when moving from stationary to flight conditions. The method breaks up the coaxial jet mixing noise into three discrete single-stream jets:

  1. The secondary jet
  2. The mixed jet
  3. The interaction jet

Each of these discrete jets is characterized by different combinations of the coaxial jet parameters.

Considering velocity alone, the single-stream jet that represents the mixed jet has a velocity that is a function of the velocity ratio, the temperature ratio and the area ratio of the coaxial jet.

The velocity of the interaction jet is taken to be the same as that of the primary (core) flow of the coaxial jet, and the velocity of the secondary jet taken to be that of the secondary (fan) flow of the coaxial jet.

The other parameters of jet temperature, jet flow area and jet diameter are treated in similar but individual ways.

The noise from each source is predicted, modified, and summed to provide a static coaxial jet noise spectrum.

Read more about this topic in an IHS Engineering360 interview with Cyrus Chinoy, head of EDSU's Aircraft Noise & Structural Dynamics Group, and Willie Bryce, a member of the organization's Aircraft Noise Committee.

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Join Date: Oct 2008
Posts: 42296
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#1

Re: How to Predict In-flight Coaxial Jet Noise

04/05/2015 3:21 PM

I'd say the larger problem is how to reduce the perceived noise at the listener's ears.

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