On Applicability of Additive Technology in Producing Nozzles for Jet Noise Investigations

Abstract

The split-type conical nozzles with replaceable exit sections with diameters of 30, 40 and 50 mm were designed and produced from steel by machine turning. In addition, the replaceable output parts of the nozzles with the same diameters were produced by additive technology (fused deposition manufacturing) from ABS plastic. In the acoustic anechoic chamber, the noise measurements of a single-stream cold air jet for all the nozzles at jet velocities in the range of 0.3-0.7 Mach numbers were carried out. The noise measurements were performed on distance of 2 m from the center of the nozzle exit section at angles from 30 to 105o. For different directions of noise radiation and different velocities of the jet, the power spectral density and overall sound pressure level were determined. The obtained results demonstrates that the jet noise for nozzles with diameter of 40 and 50 mm from steel and ABS plastic differs by no more than 1 dB, which is within the measurement error for these types of experiments. The nozzles with diameter 30 mm have a higher difference in noise, which can be explained by the more sensitivity of a nozzle with a small diameter to the deviations of geometric parameters when it produced by additive technology.

On the influence of lateral cells and local perforation of resonance liner samples on the accuracy of determining their acoustic characteristics in experimental studies

“…Due to the disadvantages of semiempirical models indicated in the introduction, the prediction of the acoustic characteristics of the selected samples was carried out on the basis of numerical modeling of physical processes in a normal incidence interferometer with a liner sample, the features of which are briefly indicated in the next section. The technique used has proven itself well, including for resonant multilayer liner [17][18][19].…”

“…The diameter of the designed samples of 30 and 50 mm was due to the diameter of the channel cross-sections of interferometers with normal incidence used in experimental studies [18]. The interferometer is a cylindrical tube, at one end of which a liner sample is located, and at the other end there is a speaker that irradiates the sample with an acoustic signal at sound pressure levels of 120-155 dB.…”

“…The geometry of the liner sample corresponded to the design geometric parameters presented in Tables 1 and 2. The modeling technique is described in more detail in [17][18][19]. In this study, the formulations of the calculation are considered when an acoustic wave is incident on only one honeycomb resonator in a channel with a diameter of 16.4, 30 and 50 mm (Fig.…”

Study of the Position of Sound Sources in a Turbulent Jet Using Nozzles of Different Configurations

“…The conical nozzle is a 12-degree taper and has a sharp cut edge. A detailed study of the noise of a jet outflowing from the used conical nozzles is considered in [26,27]. The chevron nozzle used in this work had 12 chevrons located along the nozzle output contour [28].…”