Sound insulation of fuselage aircraft structures with different composition of resonant elements

The problem of reducing noise in the cabin of a propeller aircraft is an urgent task of internal acoustics, since traditional sound-insulating structures do not have sufficient efficiency in the region of low frequencies. One of the promising ways to solve it is the use of resonant systems, with the help of which it is possible to significantly increase the sound insulation of the fuselage structure of the aircraft in this frequency range. In this work, the effect of resonant systems on the sound-insulating ability of flat and cylindrical panels without and with cross stiffening simulating the body bulkhead frame was experimentally determined, as well as the effectiveness of lining the passenger compartment with resonant systems of various compositions was determined. Tests were carried out in sound chambers and on a full-scale stand, which is a real passenger plane. When facing the tested structures, elasto-acoustic compensators of various types with resonant elements made using foil, micalent paper and thermo-polyurethane were used. It is shown that the efficiency of resonant systems can reach 10–20 decibels or more.