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Hydrodynamic and Acoustic Waves from Vortex Generators Noise Reduction for Supersonic Jets

Saleem, Mohammad
http://orcid.org/0009-0001-4168-2875
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721397255006065

Abstract Details

2024, PhD, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
An experimental investigation into the wave sources responsible for the noise generation mechanisms of supersonic jet noise and their mitigation using MVG nozzles is presented. Flow field measurements using PIV revealed that MVGs mitigate noise through two mechanisms; they generate internal oblique shock waves that weakens the shock cell, and they substantially increase the shear layer mixing and its entrainment of ambient fluid which reduces the length scales and velocities of the convecting coherent structures. In addition, time-resolved Schlieren visualizations were spectrally analyzed to decompose and reconstruct the hydrodynamic waves in the flow field and the generation process of the acoustic wave emission directly from the jet providing insights into the noise generation mechanism and their suppression by inducing the peak wave instabilities to shift to larger wavenumber values to reduce their acoustic emission efficiencies, which were confirmed by acoustic measurements. The findings from this investigation show direct visualization of the acoustic wave emission from the sources in the flow field. These waves have downstream components that are emitted from the modulation of the shear layer inducing spatial coherence of the turbulent vortical structures. This modulation is induced by the passing of the upstream acoustic waves along the shear layer from all shock cells synchronized as a phased array with regions of constructive and destructive interference patterns which steers the emitted acoustic radiation beams. The intense acoustic beam perturbs the shear layer and induces the formation of the internal trapped waves with phase velocities propagating upstream of the supersonic jet flow. Based on these findings, new noise generation mechanisms are proposed that cover various aspects of the physical mechanisms of jet noise components for the turbulent mixing noise, the broadband shock associated noise and the screech resonance tone, along with reduction and suppression mechanisms.
Ephraim Gutmark, Ph.D. (Committee Chair)
Junhui Liu, Ph.D. (Committee Member)
Shaaban Abdallah, Ph.D. (Committee Member)
Paul Orkwis, Ph.D. (Committee Member)
197 p.
Aerospace Engineering
jet noise; reduction; shock waves; wavenumber; vortex generator; supersonic

Recommended Citations

Citations

  • Saleem, M. (2024). Hydrodynamic and Acoustic Waves from Vortex Generators Noise Reduction for Supersonic Jets [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721397255006065

    APA Style (7th edition)

  • Saleem, Mohammad. Hydrodynamic and Acoustic Waves from Vortex Generators Noise Reduction for Supersonic Jets. 2024. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721397255006065.

    MLA Style (8th edition)

  • Saleem, Mohammad. "Hydrodynamic and Acoustic Waves from Vortex Generators Noise Reduction for Supersonic Jets." Doctoral dissertation, University of Cincinnati, 2024. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1721397255006065

    Chicago Manual of Style (17th edition)

ucin1721397255006065
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© 2024, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12