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Far-field radiated noise mechanisms in high reynolds number and high-speed jets

Kastner, Jeffrey F.
http://rave.ohiolink.edu/etdc/view?acc_num=osu1181753004

Abstract Details

2007, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
The present research examines the relationship between the large-scale structure dynamics of a jet and the far-field sound. This was achieved by exploring the flowfield and the far field of an axisymmetric Mach 0.9 jet with a Reynolds number of approximately 0.76 million. The jet is controlled by eight plasma actuators, which operate over a large frequency range and have independent phase control allowing excitation of azimuthal modes (m) 0, 1, 2, and 3. The jet’s far field is probed with a microphone array positioned at 30 degrees with respect to the downstream jet axis. The array is used to estimate the origin of peak sound events in space, and find the sound pressure level (SPL) and overall sound pressure level (OASPL). The lower forcing Strouhal numbers (StDF’s) increase the OASPL and move noise sources upstream while higher StDF’s decrease the OASPL and have noise source distributions similar to the baseline jet. The flowfield was investigated using particle image velocimetry (PIV). A Reynolds decomposition of the PIV data emphasized the importance of the streamwise velocity fluctuations for the symmetric azimuthal modes (m = 0 and 2) and the cross-stream velocity fluctuations for the asymmetric azimuthal modes (m = 1 and 3). A proper orthogonal decomposition of the PIV data was performed to extract information about how forcing affects the large-scale flow features and conditionally average the PIV data. When forcing at StD’s other than the preferred mode, the conditional-averaged images show large-scale flow features that grow, saturate, and decay closer to the nozzle exit. When exciting a symmetric azimuthal mode, m = 0, near the preferred StDF, the streamwise phase-averaged velocity grows quickly and saturates over a relatively long spatial range. When exciting an asymmetric azimuthal mode, m = 1, near the preferred StDF, the cross-stream phase-averaged velocity grows slowly, saturates, and then decays relatively quickly. The noise source distribution occurred in the decay region for both m = 0 and m = 1, and the distribution changed in accordance with changes in the decay rate.
Mo Samimy (Advisor)
Engineering, Mechanical
Fluid Dynamics; Gas Dynamics; Aeroacoustics; Optical Diagnostics

Recommended Citations

Citations

  • Kastner, J. F. (2007). Far-field radiated noise mechanisms in high reynolds number and high-speed jets [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1181753004

    APA Style (7th edition)

  • Kastner, Jeffrey. Far-field radiated noise mechanisms in high reynolds number and high-speed jets. 2007. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1181753004.

    MLA Style (8th edition)

  • Kastner, Jeffrey. "Far-field radiated noise mechanisms in high reynolds number and high-speed jets." Doctoral dissertation, Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=osu1181753004

    Chicago Manual of Style (17th edition)

osu1181753004
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© 2007, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.