Experimental Investigation on the Effect of Chevron Penetration on 4 Lobed Chevron Nozzles

Tide P.S., Srinivasan K
2009 47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition   unpublished
Experimental investigations have been carried out on 4 lobed chevron nozzles to asses the importance of chevron penetration on noise reduction benefits. Acoustic measurements such as overall sound pressure level, spectra and directivity of sound pressure have been carried out for chevron nozzle configurations over a range of nozzle pressure ratios from 1.5 to 5, that correspond to fully expanded jet Mach number varying in between 0.75 and 1.70. Shadowgraph images of the shock-cell structure of
more » ... -cell structure of jets from chevron nozzles have also been captured for various nozzle pressure ratios and compared. Of all the geometries studied, chevron nozzle with 4 lobes and 10 • penetration angle gives the maximum noise reduction, especially at higher pressure ratios. Chevron nozzles with lower penetration give marginal noise reduction for all emission angles. Chevron nozzles are found to be free from screech unlike regular nozzles. Also the directivity measurements show that chevron nozzles are directive at 50 • to the jet exit axis. The results indicate that a higher level of penetration yields better noise reduction, especially at higher nozzle pressure ratios.
doi:10.2514/6.2009-852 fatcat:wckaghbkbnecjgljrrl44zjale