PunekarAvitalRona3085639.pdf (695.42 kB)
Skewness as means for separating crackle from screech
conference contribution
posted on 2019-06-10, 14:10 authored by Jyothi Punekar, Eldad J. Avital, Aldo RonaScreech and crackle are investigated by far-field acoustic measurements and visualizations of a cold jet fromaMach 2 convergent-divergent nozzle operated over-expanded, fully expanded, and under-expanded. The skewness of the sampled far-field pressure frequency distribution is evaluated at polar angles below 90°. It is found that skewness alone is insufficient for singling out crackling noise, however, a better characterization is obtained by jointly considering the skewness of the acoustic pressure time derivative. New evidence is provided of crackle and screech being competitive mechanisms over the nozzle pressure ratio range 4:3 to 10. These new physical insights advance the current understanding of high-speed jet aeroacoustics, towards enabling sustainable airport operations of supersonic civil aircraft.
Funding
This work was internally funded by Queen Mary University of London and by the University of Leicester, at which Punekar holds honorary positions. Collaboration amongst authors was supported by a Short Research Visit award by UK Fluids, under EPSRC grant EP/N032861/1. The technical support of Dr F. Motallebi for producing the schlieren records and of Mr P. D. Williams, for the signal acquisition hardware set-up, are gratefully acknowledged. The authors acknowledge early discussions with the late Prof. G. M. Lilley on screech and crackle, which have inspired them to undertake this research.
History
Citation
2019 AIAA/CEAS Aeroacoustics Conference, 2019, pp. 1-12Author affiliation
/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of EngineeringSource
2019 AIAA/CEAS Aeroacoustics Conference, TUDelft, NetherlandsVersion
- AM (Accepted Manuscript)
