Publication: Aeroacoustic studies of underexpanded pipe jets
Abstract
Experimental investigations on the acoustic characteristics of underexpanded pipe jets of 10mm diameter are carried out. Pipe of lengths L = 10 mm and L = 60 mm are considered for the study. Acoustic characteristics in terms of the spectra, directivity of sound pressure, broadband shock associated noise properties are obtained to unravel the basic differences of 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. Spectral and tonal analysis results reveal that the screech tones are suppressed with increase in length of pipe. Further, the broadband shock associated noise increases with increase in the pipe length. Copyright © 2009 by the American Institute of Aeronautics and Astronautics, Inc.