US 12,170,077 B2
Acoustic attenuation panel for low-frequency waves
Marc Versaevel, Moissy Cramayel (FR); Bertrand Desjoyeaux, Moissy Cramayel (FR); and Mathieu Preau, Moissy Cramayel (FR)
Assigned to Safran Nacelles, Gonfreville l'Orcher (FR)
Filed by Safran Nacelles, Gonfreville l'Orcher (FR)
Filed on Apr. 8, 2022, as Appl. No. 17/716,089.
Application 17/716,089 is a continuation of application No. PCT/FR2020/051712, filed on Sep. 30, 2020.
Claims priority of application No. 19/11130 (FR), filed on Oct. 8, 2019.
Prior Publication US 2022/0230613 A1, Jul. 21, 2022
Int. Cl. G10K 11/172 (2006.01); B64D 33/02 (2006.01)
CPC G10K 11/172 (2013.01) [B64D 33/02 (2013.01); B64D 2033/0206 (2013.01)] 14 Claims
OG exemplary drawing
 
1. An acoustic attenuation panel comprising:
a perforated acoustic wall;
a first honeycomb structure coupled to the perforated acoustic wall, the first honeycomb structure comprising a plurality of acoustic cells delimited by peripheral partitions;
a second honeycomb structure comprising a plurality of acoustic cells delimited by peripheral partitions; and
a septum comprising a plurality of macro-perforations interposed between said first honeycomb structure and said second honeycomb structure,
each acoustic cell of the first honeycomb structure and each acoustic cell of said second honeycomb structure being disposed opposite a unique perforation of the septum,
wherein the macro-perforations are evenly distributed in the septum such that three adjacent macro-perforations form an equilateral triangle one side of which is equal to a diameter of the acoustic cells of the first and second honeycomb structures, and one height of which is equal to 0.86 times the diameter of the acoustic cells of the first and second honeycomb structures +/−20%.