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Spectral Energy Transfers in Transonic Cavity Flows with High Frequency Flow Control from Powered Resonance Tubes

Abolmoali, Philip
http://orcid.org/0000-0001-8205-0797
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867795447293

Abstract Details

2017, PhD, University of Cincinnati, Engineering and Applied Science: Aerospace Engineering.
The oscillatory flow within weapons bay cavities of military aircraft produces broadband noise superimposed by intense, low frequency tones, particularly during transonic flight. Passive control devices such as leading edge spoilers, while effective during subsonic flight, display diminished effectiveness with increasing Mach number. Alternatively, introduction of leading edge perturbations to the cavity shear layer at frequencies on the order of 10 times the dominant tonal frequency have shown promise, resulting in attenuations of up to 29 dB in wind tunnel studies [1]. This thesis provides a new perspective on the physics of “high-frequency” flow control by examining the couplings amongst the spatial scales of the flow using higher-order spectral analysis and performing low-dimensional modal analysis. In particular, the methods of bispectral analysis and Dynamic Mode Decomposition were selected for their capability to identify underlying processes in non-linear physical systems. The present study calculates acoustic power spectra at selected axial stations along the cavity walls, and the cross-bispectrum associated with unsteady axial velocity calculations along the cavity shear layer to identify quadratic phase couplings between spectral components. Subsequently, spatial structures associated with power spectral components are extracted by performing Dynamic Mode Decomposition (DMD) [9, 10] upon a discrete snapshot set sampled from the flow at equispaced time intervals. In the present study, numerical simulations of uncontrolled and controlled M=1.19 flow traversing an L/D = 5.0, W/D = 0.5 rectangular cavity are performed. Five controlled simulations are made which approximate the presence of a leading edge, resonance tube bank issuing normal to the freestream. For a pulsing frequency of 5 kHz, blowing ratios of ß=1.2,0.6,0.3 are investigated to isolate the effect of frequency on acoustic power spectra. For a blowing ratio ß=1.2, pulsing frequencies of 1 kHz and 5 kHz are made to distinguish between “low-frequency” and “high-frequency” effects. Finally, a steady blowing simulation is made for a blowing ratio ß=1.2. Detached Eddy Simulations for the aforementioned cases are performed using FDL3DI [55], a three-dimensional, unsteady, compressible Navier-Stokes solver, pioneered at the Air Force Research Laboratory.
Awatef Hamed, Ph.D. (Committee Chair)
Kelly Cohen, Ph.D. (Committee Member)
Ephraim Gutmark, Ph.D. D.Sc. (Committee Member)
Jeffrey Kastner, Ph.D. (Committee Member)
276 p.
Aerospace Materials
Cavity; High-Frequency; DMD; Bispectral; CFD; Control

Recommended Citations

Citations

  • Abolmoali, P. (2017). Spectral Energy Transfers in Transonic Cavity Flows with High Frequency Flow Control from Powered Resonance Tubes [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867795447293

    APA Style (7th edition)

  • Abolmoali, Philip. Spectral Energy Transfers in Transonic Cavity Flows with High Frequency Flow Control from Powered Resonance Tubes. 2017. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867795447293.

    MLA Style (8th edition)

  • Abolmoali, Philip. "Spectral Energy Transfers in Transonic Cavity Flows with High Frequency Flow Control from Powered Resonance Tubes." Doctoral dissertation, University of Cincinnati, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511867795447293

    Chicago Manual of Style (17th edition)

ucin1511867795447293
225
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This open access ETD is published by University of Cincinnati and OhioLINK.