Abstract
A rapid development of civil aviation and air transportation market is going on in the XXI century, which is a catalyst for the growth of urban and regional economies. At the same time, the negative impact of aviation on the environment is intensifying, especially in the near-aerodrome territories. The ecology of aviation has become the second most important issue highlighted by the International Civil Aviation Organization, giving way to safety only. One of the dominant components of the aviation harmful effects on the environment is the noise created by the aircraft on the ground. The International Civil Aviation Organization is constantly tightening international standards for aircraft noise on the ground, normalizing its level on take-off and landing modes, forcing aircraft manufacturers to develop new aircraft noise reduction technologies. One of the main components of aircraft noise is the noise generated by propulsion systems. To successfully solve the problems of reducing the aircraft engine noise in a given frequency range, it becomes necessary to conduct complex computational and experimental research to evaluate and optimize sound attenuation in model channels. In addition, it is necessary to research the Helmholtz resonator and SAS parameters effect on the impedance, taking into account the acoustic mechanisms laws and non-linear processes of interactions between the noise and the channel walls. Based on the research, it is necessary to develop new effective forms, hybrid layouts and sizes of the SAS resonant cells. In the present work, physical and mathematical models were formulated for predicting the effective acoustic characteristics of cone-shaped resonators in non-linear operating modes. The results of computational and experimental research of cone-shaped sound-absorbing structures samples on an interferometer with a normal sound wave incidence at a sound pressure level of 130 dB are presented. It was revealed that during the joint operation of cone-shaped resonators, the effect of mutual influence on the SAS nonlinear operating modes was not observed. It was found that the combination of a cone-shaped and an inverted cone-shaped resonator leads to a significant increase in broadband in the SAS non-linear operating modes. The acoustic efficiency of coneshaped resonators was experimentally confirmed. The verification of the developed models was carried out.
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