Hostname: page-component-7dd5485656-s6l46 Total loading time: 0 Render date: 2025-10-30T18:18:49.398Z Has data issue: false hasContentIssue false
  • English
  • Français

Pressure fluctuations due to ‘trapped waves’ in the initial region of compressible jets

Published online by Cambridge University Press:  29 November 2021

K.B.M.Q. Zaman Open the ORCID record for K.B.M.Q. Zaman [Opens in a new window] ,
A.F. Fagan  and
P. Upadhyay Open the ORCID record for P. Upadhyay [Opens in a new window]
K.B.M.Q. Zaman*
Affiliation:
Inlets and Nozzles Branch, NASA Glenn Research Center, Cleveland, OH 44135, USA
A.F. Fagan
Affiliation:
Optics and Photonics Branch, NASA Glenn Research Center, Cleveland, OH 44135, USA
P. Upadhyay
Affiliation:
Inlets and Nozzles Branch (with HX5 LLC), NASA Glenn Research Center, Cleveland, OH 44135, USA
*
†Email address for correspondence: khairul.b.zaman@nasa.gov
Get access Rights & Permissions [Opens in a new window]

Abstract

An experimental study is conducted on unsteady pressure fluctuations occurring near the nozzle exit and just outside the shear layer of compressible jets. These fluctuations are related to ‘trapped waves’ within the jet's potential core, as investigated and reported recently by other researchers. Round nozzles of three different diameters and rectangular nozzles of various aspect ratios are studied. The fluctuations manifest as a series of peaks in the spectra of the fluctuating pressure. Usually the first peak at the lowest frequency (fundamental) has the highest amplitude and the amplitude decreases progressively for successive peaks at higher frequencies. These ‘trapped wave spectral peaks’ are found to occur with all jets at high subsonic conditions and persist into the supersonic regime. Their characteristics and variations with axial and radial distances, jet Mach number and aspect ratio of the nozzle are documented. For round nozzles, the frequency of the fundamental is found to be independent of the jet's exit boundary layer characteristics and scales with the nozzle diameter. On a Strouhal number (based on diameter) versus jet Mach number plot it is represented by a unique curve. Relative to the fundamental the frequencies of the successive peaks are found to bear the ratios of 5/3, 7/3, 9/3 and so on, at a given Mach number. For rectangular nozzles, the number of peaks observed on the major axis is found to be greater than that observed on the minor axis by a factor approximately equal to the nozzle's aspect ratio; the fundamental is the same on either edge. For all nozzles the onset of screech tones appears as a continuation of the evolution of these peaks; it is as if one of these peaks abruptly increases in amplitude and turns into a screech tone as the jet Mach number is increased.

JFM classification

Acoustics: Jet noise Acoustics: Aeroacoustics

Information

Type
JFM Papers
Information
Journal of Fluid Mechanics , Volume 931 , 25 January 2022 , A30
Check for updates
Copyright
© The Author(s), 2021. Published by Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Article purchase

Temporarily unavailable

References

Bogey, C. 2021 Acoustic tones in the near nozzle region of jets: characteristics and variations between two Mach numbers 0.5 and 2. J. Fluid Mech. 921, A3.CrossRefGoogle Scholar
Brès, G.A., Jaunet, V., Rallic, M.L., Jordan, P., Colonius, T. & Lele, S.K. 2015 Large eddy simulation for jet noise: the importance of getting the boundary layer right. AIAA Paper 2015-2535.CrossRefGoogle Scholar
Brès, G.A., Jordan, P., Jaunet, V., Rallic, M.L., Cavalieri, A.V.G., Towne, A., Lele, S.K., Colonius, T. & Schmidt, O.T. 2018 Importance of the nozzle-exit boundary-layer state in subsonic turbulent jets. J Fluid Mech. 851, 83–124.CrossRefGoogle Scholar
Edgington-Mitchell, D., Jaunet, V., Jordan, P., Towne, A., Soria, J. & Honnery, D. 2018 Upstream-travelling acoustic jet modes as a closure mechanism for screech. J Fluid Mech. 855, R1.CrossRefGoogle Scholar
Edgington-Mitchell, D., Wang, T., Nogueira, P., Schmidt, O.T., Jaunet, V., Duke, D., Jordan, P. & Towne, A. 2021 Waves in screeching jets. J. Fluid Mech. 913, A7.CrossRefGoogle Scholar
Esfahani, A.G., Webb, N.J. & Samimy, M. 2021 Coupling modes in supersonic twin rectangular jets. AIAA Paper 2021-1292.Google Scholar
Fagan, A.F. & Zaman, K.B.M.Q. 2020 Rayleigh-scattering-based study of ‘trapped waves’ in high-speed jets AIAA Paper 2020-2524.CrossRefGoogle Scholar
Jordan, P., Jaunet, V., Towne, A., Cavalieri, A.V.G., Colonius, T., Schmidt, O.T. & Agarwal, A. 2018 Jet–flap interaction tones. J. Fluid Mech. 853, 333–358.CrossRefGoogle Scholar
Liu, J., Corrigan, A.T., Johnson, R.F. & Ramamurti, R. 2019 Effect of nozzle inflow conditions on shock-cell structure and noise in overexpanded jets. AIAA Paper 2019-2495.CrossRefGoogle Scholar
Mancinelli, M., Jaunet, V., Jordan, P. & Towne, A. 2019 Screech-tone prediction using upstream-travelling jet modes. Exp. Fluids 60, 22.CrossRefGoogle Scholar
Michalke, A. 1970 A note on the spatial jet-instability of the compressible cylindrical vortex sheet. DLR Report FB-70-51.Google Scholar
Michalke, A. 1984 Survey on jet instability theory. Prog. Aerosp. Sci. 21, 159–199.CrossRefGoogle Scholar
Morris, P.J. 2010 The instability of high speed jets. Intl J. Aeroacoust. 9 (1), 1–50.CrossRefGoogle Scholar
Norum, T.D. 1984 Control of jet shock associated noise by a reflector. AIAA Paper 84-2279.CrossRefGoogle Scholar
Panda, J., Raman, G. & Zaman, K.B.M.Q. 1997 Underexpanded screeching jets from circular, rectangular and elliptic nozzles. AIAA Paper 97-1623.Google Scholar
Raman, G. 1997 Cessation of screech in underexpanded jets. J. Fluid Mech. 336, 69–90.CrossRefGoogle Scholar
Raman, G. 1999 Supersonic jet screech: half century from Powell to the present. J. Sound Vib. 225 (3), 543–571.CrossRefGoogle Scholar
Schmidt, O.T., Towne, A., Colonius, T., Cavalieri, A.V.G., Jordan, P. & Brès, G.A. 2017 Wavepackets and trapped acoustic modes in a turbulent jet: coherent structure eduction and global stability. J. Fluid Mech. 825, 1153–1181.CrossRefGoogle Scholar
Shen, H. & Tam, C.K.W. 2002 Three-dimensional numerical simulation of the jet screech phenomenon. AIAA J. 40 (1), 33–41.CrossRefGoogle Scholar
Suzuki, T. & Colonius, T. 2006 Instability waves in a subsonic round jet detected using a near-field phased microphone array. J. Fluid Mech. 565, 197–226.CrossRefGoogle Scholar
Tam, C.K.W. & Ahuja, K.K. 1990 Theoretical model of discrete tone generation by impinging jets. J. Fluid Mech. 214, 67–87.CrossRefGoogle Scholar
Tam, C.K.W. & Chandramouli, S. 2020 Jet-plate interaction tones relevant to over-the-wing engine mount concept. J. Sound Vib. 486 (10), 115378.CrossRefGoogle Scholar
Tam, C.K.W. & Hu, F.Q. 1989 On the three families of instability waves of high speed jets. J. Fluid Mech. 201, 447–483.CrossRefGoogle Scholar
Towne, A., Cavalieri, A.V.G., Jordan, P., Colonius, T., Schmidt, O.T., Jaunet, V. & Brès, G.A. 2017 Acoustic resonance in the potential core of subsonic jets. J. Fluid Mech. 825, 1113–1152.CrossRefGoogle Scholar
Zaman, K.B.M.Q. 1999 Spreading characteristics of compressible jets from nozzles of various geometries. J. Fluid Mech. 383, 197–228.CrossRefGoogle Scholar
Zaman, K.B.M.Q. 2012 Flow field surveys for various rectangular nozzles. NASA Tech. Memo. 2012-217410.CrossRefGoogle Scholar
Zaman, K.B.M.Q. 2019 Exit boundary layer data for a round convergent nozzle in support of numerical simulation efforts. NASA Tech. Memo. 2019-220242.Google Scholar
Zaman, K.B.M.Q. & Fagan, A.F. 2019 Near-exit pressure fluctuations in jets from circular and rectangular nozzles, NASA Tech. Memo. 2019-220383.Google Scholar
Zaman, K.B.M.Q. & Fagan, A.F. 2020 Pressure fluctuations due to ‘trapped waves’ in the initial region of high-speed jets. AIAA Paper 2020-2523.CrossRefGoogle Scholar
Zaman, K.B.M.Q., Fagan, A.F., Bridges, J.E. & Brown, C.A. 2015 An experimental investigation of resonant interaction of a rectangular jet with a flat plate. J. Fluid Mech. 779, 751–775. doi:10.1017/jfm.2015.453CrossRefGoogle Scholar