Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


MastersThesis_Malkus_2021.pdf (74.06 MB)

ETD Abstract Container

Abstract Header

Effect of Submergence on the Flow Around a Canonical Hemisphere at Transonic Conditions

Malkus, Mikala Juliet
http://orcid.org/0000-0002-5812-9566
http://rave.ohiolink.edu/etdc/view?acc_num=osu1638901648360645

Abstract Details

2022, Master of Science, Ohio State University, Aerospace Engineering.
The effect of varying submergence on the transonic flow past canonical wall-mounted hemispheres is investigated at a freestream Mach number, M = 0.8 using Delayed Detached Eddy Simulations (DDES). Four submergence levels are considered ranging from a full hemisphere (100% exposed) to a highly submerged case where the equator is well below the waterline (40% exposed). Analysis of the mean characteristics indicates a reduction in strength and extent of dominant flow topology, including the horseshoe vortex and the counter-rotating vortices in the wake. Additionally, it is found that the mean line of surface separation moves downstream with submergence. This finding is validated with analysis of the unsteady streamwise shock position, which indicates the mean shock foot position also moved downstream with submergence. However, the frequency associated with the streamwise motion of the shock remains consistent between the cases in terms of a suitably non- dimensionalized Strouhal number, StD ∼ 0.26. The unsteady surface forces and modal analysis are used to quantify the effect of submergence on two correlated shock-wake modes, as these are dominant unsteady features in flow over full hemispheres. The first mode is the “breathing” mode, corresponding to spanwise symmetric wake shedding and correlates to streamwise shock oscillations. The second mode is the “shifting”, corresponding to spanwise anti-symmetric wake shedding and correlates with the spanwise rocking of the shock. Proper Orthogonal Decomposition (POD) is used to isolate and rank the different modes; as the hemisphere is submerged, there is an evident change in prominence from the anti-symmetric shifting to the symmetric breathing mode. Dynamic Mode Decomposition (DMD) is used to investigate the spectral content of these modes; the results show that the breathing mode collapses at a frequency of StD ∼ 0.26 for all cases, while the shifting mode extends over a broad frequency range of StD between 0.13 and 0.21.
Jack McNamara (Committee Member)
Datta Gaitonde (Advisor)
61 p.
Aerospace Engineering
Modal decomposition; canonical hemisphere; transonic flow; shock boundary layer interaction

Recommended Citations

Citations

  • Malkus, M. J. (2022). Effect of Submergence on the Flow Around a Canonical Hemisphere at Transonic Conditions [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638901648360645

    APA Style (7th edition)

  • Malkus, Mikala. Effect of Submergence on the Flow Around a Canonical Hemisphere at Transonic Conditions. 2022. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1638901648360645.

    MLA Style (8th edition)

  • Malkus, Mikala. "Effect of Submergence on the Flow Around a Canonical Hemisphere at Transonic Conditions." Master's thesis, Ohio State University, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=osu1638901648360645

    Chicago Manual of Style (17th edition)

osu1638901648360645
61
© 2021, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.