Study of Acoustic Barriers with an Cylindrical Top Edge for Reducing the Noise of Power Equipment

Abstract

Acoustic barriers are used to reduce the noise of power equipment. To increase their efficiency, an cylindrical top edge is installed, which is an add-on on the top edge of the barrier. To study the acoustic properties of the cylindrical top edge, a mathematical model of a 3-m high barrier was built in the COMSOL Multiphysics program. The mathematical model of the barrier without an cylindrical top edge was verified using the Kurze calculation method. The acoustic characteristics of a superstructure in the form of an cylindrical top edge have been studied. It has been determined that the acoustic efficiency of the cylindrical top edge depends both on the position relative to the upper edge of the barrier and on the distance from the noise source to the barrier. The calculation results show that the greatest changes in sound pressure levels when installing an cylindrical top edge are observed at high frequencies, and the minimum at low frequencies. The acoustic efficiency of the cylindrical top edge at geometric mean frequencies corresponding to low frequencies is approximately 1–2 dB and it can reach up to 25 dB at geometric mean frequencies corresponding to high frequencies. The acoustic characteristics of an cylindrical top edge with different installation angles have been studied. It has been shown that the cylindrical top edge with an installation angle of 0° has the highest acoustic efficiency (8–10 dBA) at a distance from the noise source to the barrier of up to 2 m. At distances from 2 to 5 m, the highest acoustic efficiency (4–8 dBA) is observed when using an antidiffraction device with an installation angle of 90°. Using an cylindrical top edge with an installation angle 180° is advisable when the barrier is located next to the design point at a distance from the barrier to it of less than 5 m. When installing an antidiffraction device, a significantly greater acoustic effect is achieved than when increasing the height of the barrier. The results obtained during the research are recommended to be taken into account when implementing noise reduction measures when choosing the location of an acoustic barrier with an cylindrical top edge relative to the noise source and the design point.