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The noise of jets formed using conical and lobed nozzles has been measured. The possibility of jet noise reduction by using a lobed nozzle shape has been demonstrated. The localization of noise sources in jets formed using various nozzles has been carried out. A planar 9-beam 54-channel Bruel & Kjaer micro-phone array and Delay-and-Sum Beamforming technique were used. As a result, the position of noise sources in a turbulent jet in one-third octave frequency bands was obtained. The deviation effect of the position of noise sources when using lobed nozzles relative to the standard jet formed by a conical nozzle is demonstrated.

The aim of this work is to study the position of dominant sound sources in a small-scale turbulent jet using the beamforming method. Two nozzles of equivalent diameter and different geometric configurations (conical and chevron) were used to create different initial conditions for the outflow. Based on the analysis of the results obtained, it can be concluded that they are in good agreement with the well-known concepts of the physics of noise generation processes by turbulent jets: higher-frequency sources are generated by smaller-scale turbulent structures located closer to the nozzle edge, which is confirmed by the localization of high-frequency noise sources also closer to the nozzle edge. The chevron nozzles loosen the initial section of the jet, making it less short and thereby facilitating a faster displacement of noise sources to the nozzle edge, as seen when comparing localization maps for conical and chevron nozzles at the same frequencies. The results of localization were compared with the data obtained by other researchers. The results obtained were found to provide confidence in the use of acoustic beamforming to measure the location of the jet noise source with accuracy similar to other methods that have been used in the past.