Scientists at the Perm National Research Polytechnic University (PNRPU) have designed a “smart” noise-canceling structure with effective sound absorption in a wide frequency range, the university’s press service reported on April 27.
The development of the Perm Polytechnic University will help to ensure that the products of domestic aircraft engine manufacturers meet the requirements of the International Civil Aviation Organization for the level of sound absorption in aircraft engines.
Noise suppression structures, which have become an indispensable element of modern aircraft engines, are a cellular structure made of polymer composite materials, in which acoustic waves are absorbed due to their resonant interaction.
The results of the study of the effective design for noise reduction proposed by the PNRPU scientists were presented in the article “Acoustic interactive of piezo-adaptive resonant cells of a sound-absorbing honeycomb panel”, published in the Russian Aeronautics journal (No. 65, 2022).
To reduce noise in the front hemisphere of the engine, resonant cell honeycomb panels of sound-absorbing structures are placed on the inner surface of the air intake, and to reduce noise in the rear hemisphere of the engine, they are placed on the walls. from the outside air duct.
The design of the panels is based on calculations of their ability to counteract sound waves in an aircraft’s engine channels. For such a calculation, PNRPU scientists have developed a model for the operation of a single cell of a noise canceling structure and a group of such cells. In it, they took into account its parameters, which were not taken into account before.
Computational experiments carried out by them, in which, by varying the diameter of the perforation in the cells, made it possible to determine the scheme of their mutual arrangement, which provided the best noise absorption.
project leader i Head of the Department of Mechanics of Composite Materials and Structures, PNRPU, Lead Researcher of the Research Laboratory of Spatially Reinforced Composite Materials, Ph.D. Pavel Pisarev spoke about the work they have done:
“To implement the identified schemes, we developed an adaptive control model of the resonant frequencies of the cells through piezoactive elements integrated into the borehole, which are capable of converting mechanical stress into electrical charge and vice versa. Thus, the piezoactive elements transform the electrical voltage that is applied to them into deformations that modify the diameter of the necks of the adaptive resonators..
He explained that the combinations of drilling diameters and arrangements of relative arrangement of elements determined by them will help in the design of effective noise damping structures, including adaptive ones.
Scientists from Perm Polytechnic University verified the results of mathematical modeling with experimental data. The study confirmed that the proposed design has effective sound absorption over a wide frequency range. At the same time, the increase in its weight is minimal in relation to the structures currently used, which is very important for the aeronautical industry.
The regularities of oscillatory processes in acoustic resonators revealed during the study can be used in other production areas, for example, in the design of certain types of combustion chambers, the scientists noted.
Source: Rossa Primavera
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