0
$\begingroup$

enter image description here

I read the post here: What is the function of the holes in splitter plates?

My question is, what are those hole looking things inside the engine nacelle?

It seems reasonable to me that as air enters the intake slower air would accumulate towards the outboard portion of the engine nacelle due to the shape of the leading edges. You want the air to enter the blades uniformly so you could add these pinholes which would remove the slower moving air. This would lead to more even distribution of faster moving air and subsequently better engine performance.

Am I tracking correctly?

Edit: here’s another picture enter image description here

$\endgroup$
0

1 Answer 1

-1
$\begingroup$

They are for reducing noise emissions. According to Wikipedia,

Liners are applied on the internal walls of the engine nacelle, both in the intake and by-pass ducts, and use Helmholtz resonance principle for the dissipation of incident acoustic energy.

The Helmholtz principle (Wikipedia again) can be watched (or rather heard) when blowing over a bottle which produces a sound.

Helmholtz resonators are also used to build acoustic liners for reducing the noise of aircraft engines, for example. These acoustic liners are made of two components: a simple sheet of metal (or other material) perforated with little holes spaced out in a regular or irregular pattern; this is called a resistive sheet; a series of so-called honeycomb cavities (holes with a honeycomb shape, but in fact only their volume matters).

Such acoustic liners are used in most of today's aircraft engines. The perforated sheet is usually visible from inside or outside the airplane; the honeycomb is just under it. The thickness of the perforated sheet is of importance, as shown above. Sometimes there are two layers of liners; they are then called "2-DOF liners" (DOF meaning Degrees Of Freedom), as opposed to "single DOF liners". (Wikipedia)

$\endgroup$
0

Not the answer you're looking for? Browse other questions tagged .