Skip to main content Accessibility help
×
Home

Effect of Mach number on the acoustic field of 2:1 elliptic-slot jet

  • S. B. Verma (a1) and E. Rathakrishnan (a1)

Abstract

The shock-structure and the related acoustic field of underexpanded jets undergoes significant changes as the Mach number Mj is increased. The present investigation is carried out to study the effect of Mach number on an underexpanded 2:1 elliptic-slot jet. Experimental data are presented for fully expanded Mach numbers ranging from 1.3 to 2.0. It is observed that the ‘cross-over’ point at the end of the first cell at low Mach numbers gets replaced by a normal shock at a highly underexpanded condition resulting in the formation of a ‘barrel’ shock along the minor-axis side with a ‘bulb’ shock formed along the major-axis side. The above change in shock structure is accompanied by a related change in the acoustic field. The amplitude of fundamental frequency along the minor-axis side grows with Mj but falls beyond Mj = 1.75. Along the major-axis side, however, the fundamental frequency does not exist at low Mach numbers. It appears at Mj = 1.75 but then falls at Mj = 2.0. The related azimuthal directivity of overall noise levels (OASPL) shows significant changes with Mj.

Copyright

References

Hide All
1. Powell, A. On the mechanism of choked jet noise, Proceedings of Physical Society of London, 1953, 66, pp 1,039–1,056.
2. Hubbard, H.H. and Lassiter, L.W. Experimental studies of jet noise, J Acoustical Soc of America, 1953, 25, (3), pp 381384.
3. Hammitt, A.G. The oscillations and noise of an overpressure sonic jet, J Aero Sci, 1961, 28, (9), pp 673680.
4. Glass, D.R. Effects of acoustic feedback in the spread and decay of supersonic jets, AIAA J, 1968, 6, (10), pp 1,890–1,897.
5. Raman, G. Screech cessation in underexpanded jets, AIAA–96–17, 2nd AIAA/CEAS aeroacoustics conference, 6–8 May 1996.
6. Ponton, M.K. and Seiner, J.M. The effects of nozzle exit lip thickness on plume resonance, J Sound and Vibration, 1992, 154, (3), pp 531549.
7. Norum, T.D. and Seiner, J.M. Broadband shock noise from supersonic jets, AIAA J, 1982, 20, (1), pp 6873.
8. Hussain, A.K.M.F. and Hussain, H.S. Elliptic jets part I: characteristics of excited and unexcited jets, J Fluid Mech, 1989, 208, pp 257320.
9. Gutmark, E. and Ho, C.M. Vortex induction and mass entrainment in a small aspect-ratio elliptic jet, J Fluid Mech, 1987, 179, pp 383405.
10. Verma, S.B. and Rathakrishnan, E. Mixing benefit and noise characteristics of notched elliptic-slot jets, AIAA paper 98–3,258, 34th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 13 July 1998, Ohio.
11. Verma, S.B. and Rathakrishnan, E. The shock-structure and acoustic field of 2:1 notched elliptic-slot jet, AIAA Paper No–99–2253, Session ABP–06, 35th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, 20–24 June 1999, Los Angeles.
12. Crighton, D.G. Instability of an elliptic jet, J Fluid Mech, 1973, 59, pp 665667.
13. Hussain, A.K.M.F. and Ramjee, V. Effects of axisymmetric contraction shape on incompressible turbulent flows, Trans ASME, J Fluids Eng, 1976, 98, pp 5859.
14. Baodanoff, D., Krothapalli, A. and Karamcheti, K.. On the mixing of a rectangular jet, J Fluid Mech, 1981, 107, pp 201220.
15. Tam, C.K.W. The shock-cell structures and screech frequency of rectangular and nonaxisymmetric supersonic jets, J Sound and Vibration, 1988, 121, (1), pp 135147.
16. Seiner, J.M., Tam, C.K.W. and Yu, J.C. Proposed relationship between broadband shock-associated noise and screech tones, J Sound and Vibration, 1986, 110, pp 309321.
17. Abdel-Fattah, A.M. Discrete tone emission from high-pressure ratio supersonic jets from C-D nozzles, AIAA Journal, 1988, 26, (3), pp 283291.
18. Schadow, K.C., Wilson, K.J., Gutmark, E. and Bicker, C.J. Near-field pressure radiation and flow characteristics in low supersonic circular and elliptic jets, Physics Fluids, 1988, 31, (9), pp 2,524–2,532.
19. Schadow, K.C., Bicker, C.J. and Gutmark, E. Near acoustic field and shock structure of rectangular supersonic jets, Experiments in Fluids, AIAA Journal, 28, (7), pp 1,163–1,170.
20. Gutmark, E., Schadow, K.C., Koshigoe, S. and Wilson, K.J. Combustion related shear flow dynamics in elliptic supersonic jets, AIAA J, 1989, 27, (10), pp 1,347–1,353.

Related content

Powered by UNSILO

Effect of Mach number on the acoustic field of 2:1 elliptic-slot jet

  • S. B. Verma (a1) and E. Rathakrishnan (a1)

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed.