Jets issuing from rectangular and elliptic disk nozzles of various aspect ratios have been studied for their noise characteristics. The overall sound pressure level and directivity were measured for these jets. The effects of aspect ratio, measurement plane (major- vs. minor-) have been analyzed. The results show that the sound pressure levels are entirely different for higher and lower aspect ratio elliptic and rectangular jets. At lower aspect ratios (AR=2:1), the noise emissions from major axis plane dominate while for higher aspect ratios jets (AR>2), the noise from minor axis plane dominate. Further, the relationship between sound pressure level and average shock-cell length is observed to be quadratic at emission angles of 30° and 90° for both rectangular and elliptic jets. © Freund Publishing House Ltd.

K. Srinivasan

Department of Mechanical Engineering

U. S.Premananda Shet

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IIT Madras

Relationship between Shock-cell Length and Noise of Jets from Rectangular and Elliptic Disk Nozzles

International Journal of Turbo and Jet Engines

Experimental investigations on the acoustic characteristics of non-circular jets are carried out. Non-circular geometries include triangular, rounded triangular, square, and elliptic configurations, with a circular jet serving as the baseline case. Acoustic characteristics in terms of the spectra, directivity of sound pressure, tonal properties, and broadband shock associated noise are obtained to unravel the basic differences in these jets. Experiments are carried out for various pressure ratios ranging from 2 to 6, corresponding to fully expanded jet Mach numbers ranging from 1.04 to 1.82. The reduced effects of screech and broadband shock associated noise in triangular and square jets render them quieter than circular jet by up to 10 dB. The broadband shock associated noise levels are higher along flat edge planes than vertex planes, at all pressure ratios. Tonal analysis of the acoustic radiation from elliptic jet reveals that the screech tones along the major axis plane are more intense than those along minor axis plane. © S. Hirzel Verlag EAA.

Acta Acustica united with Acustica

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Relationship between shock-cell length and noise of jets from rectangular and elliptic disk nozzles

Journal	Data powered by TypesetInternational Journal of Turbo and Jet Engines
Publisher	Data powered by TypesetWalter de Gruyter GmbH
ISSN	03340082
Open Access	No