ACOUSTIC STRUCTURE, ENGEL NACELLE, AIRCRAFT, METHOD OF MAKING ACOUSTIC STRUCTURE AND METHOD OF REDUCING NOISE Russian patent published in 2019 - IPC F02C7/24 F02K1/82 F02C7/45 

FIELD: acoustics.

SUBSTANCE: acoustic structure comprises a cellular structure, an acoustic screen, an acoustic waveguide, first and second acoustic partitions. Cellular structure has first and second edges, multiple walls of honeycomb structure between first and second edges, forming multiple cells. Acoustic screen is located on the second edge of the cellular structure to form an acoustic resonator, the depth of which is equal to the distance between the first edge of the honeycomb structure and the acoustic screen. Acoustic waveguide is placed in an acoustic resonator and has a solid wall which is impermeable to sound waves, having an inner and an outer surface and an input and an output edges, which determine respectively the input and output of the waveguide. First acoustic partition has an upper part connected to the output of the waveguide, and a lower part located closer to the second edge of the honeycomb structure. First acoustic partition comprises a sound-permeable wall. Second acoustic partition comprises an upper part connected to the lower part of the first acoustic partition and a lower part located closer to the second edge of the honeycomb structure. Second acoustic partition comprises a sound-permeable wall, wherein the noise index of the wall of the first acoustic baffle differs from that of the wall of the second acoustic baffle. Other inventions of the group relate to the engine nacelle containing the above acoustic structure, and to the aircraft containing such nacelle. In making the acoustic structure, a honeycomb structure is made and an acoustic shield is placed on the second edge of the honeycomb structure to form an acoustic resonator. Sound waveguide is placed in an acoustic resonator, a first acoustic partition is placed at the output of the waveguide and a second acoustic partition is placed in the lower part of the first acoustic partition. One more invention relates to noise reduction method by partial surroundings of noise source with above mentioned acoustic structure.

EFFECT: group of inventions makes it possible to increase length of cell resonator without significant increase of thickness and number of cells in acoustic structure of nacelle.

20 cl, 7 dwg