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In the next picture can be seen within the housing, near the inlet:

Front view of turbofan engine Closeup of inlet section enter image description here

kevin
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XF-91
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    Are those definitely holes and not rivets? Also what are "aerodynamic takes"? – Jamiec Oct 29 '15 at 17:21
  • Sorry, I 'm Spanish and my English is pretty bad. " aerodynamic Takes" is the literal English translation of " toma aerodinámica" in Spanish , which is what you call in English " inlet" . – XF-91 Oct 29 '15 at 17:29
  • Is there any way you can put a circle or an arrow on the photoindicating specifically what you're referring to? – TomMcW Oct 29 '15 at 17:45
  • It is done. Now that I look, yes they could be rivets... – XF-91 Oct 29 '15 at 17:51
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    My first reaction is rivets, comparing them to the rivets on the seam to the right. The circled ones do look a bit randomly spaced for rivets, though. I'm wondering if it might be the textured surface of the acoustic liner. Hopefully someone that knows for sure will answer. – TomMcW Oct 29 '15 at 18:58
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    Rivets doesn't appear always evenly spaced or aligned. – mins Oct 29 '15 at 21:17
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    It is very possible that they're holes too. For example in CF34-10E5 engine the nacelle inlet is full of small holes. Unfortunately I have no idea what they are there for. – Sami Oct 29 '15 at 21:36
  • Could serve to absorb the boundary layer? – XF-91 Oct 29 '15 at 21:40
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    @Sami the many small holes further downstream in the inlet serve to reduce the noise. – fooot Oct 29 '15 at 21:46
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    My eye immediately went to the 6 dark spots on the spinner, which could be holes, and thought "That's a good question!". I guess I was looking at the wrong holes. – FreeMan Oct 30 '15 at 15:45
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    The holes on the spinner are actually for access to the bolts that hold the tip of the spinner in place. You remove that plate to get inside the spinner. – Sports Racer May 19 '17 at 18:41
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    Here's a picture of how the spinner is attached .http://imgur.com/a/lWLHq – Sports Racer May 19 '17 at 18:48
  • the circled points are definitelly rivets, they are pretty smooth and flush with the inlet. No ideea about small holes for noise, but the IAE engines we use have no such holes before the fan blades – Radu094 Jun 19 '17 at 15:48
  • They look like rivets to me. – Thomas Jun 20 '17 at 22:22

3 Answers3

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These are "acoustic liners"; they allow the sound waves to get "trapped" in the holes and make the engine quieter. Sometimes chunks tear loose and they're repaired with what amounts to Bondo.

Scott Baker
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-4

This is anti-ice system. Hot air is blown in this holes and ice/snow not settle in jet engine.

Krzysztof Bobczuk
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The holes you are referring to are a part of the engine-inlet anti-icing system. These holes prevent ice accumulation around the engine inlets. Without them, the engines may ingest ice and will also encounter airflow problems. Engines require laminar airflow in order to operate efficiently.

enter image description here

Madhav Sudarshan
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