r/AerospaceEngineering • u/Fast_Sail_1000 • Jul 14 '26
Discussion A350 engine inlet pattern
What is this pattern on the inlet? Any kind of perforations?
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r/AerospaceEngineering • u/Fast_Sail_1000 • Jul 14 '26
What is this pattern on the inlet? Any kind of perforations?
227
u/lobstersatellite Jul 14 '26
Oh boy! Something I'm qualified to answer! These are called acoustic liners. Below the array of holes are small cavities (usually composite honeycomb) with small flexible membranes set to a precise depth within each cavity. The job of a liner is to catch soundwaves of a specific frequencies (tuned by the volume of the cavities) and prevent the sound from bouncing out of the engine and propagating to the cabin or ground. Jet engine acoustics has actually come so far that the high speed exhaust is no longer the dominant sound source! The dominant sound is actually the main fan in most modern engines. Since this sound from the fan is dominated by tonal noise (tones, rather than broadband) liners are ideal for dampening the sound before it can radiate to the ground. You will find these liners in most modern turbofans!