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Capitalizing on Convective Instabilities in a Streamwise Vortex-Wall Interaction

Benton, Stuart Ira
http://orcid.org/0000-0002-2442-4663
http://rave.ohiolink.edu/etdc/view?acc_num=osu1437664298

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Aero/Astro Engineering.
Secondary flows in turbomachinery and similar engineering applications are often dominated by a single streamwise vortex structure. Investigations into the control of these flows using periodic forcing have shown a discrete range of forcing frequency where the vortex is particularly receptive. Forcing in this frequency range results in increased movement of the vortex and decreased total pressure losses. Based on the hypothesis that this occurs due to a linear instability associated with the Crow instability, a fundamental study of instabilities in streamwise vortex-wall interactions is performed. In the first part of this study a three-dimensional vortex-wall interaction is computed and analyzed for the presence of convective instabilities. It is shown that the Crow instability and a range of elliptic instabilities exist in a similar form as to what has been studied in counter-rotating vortex pairs. The Crow instability is particularly affected by the presence of a solid no-slip wall. Differences in the amplification rate, oscillation angle, Reynolds number sensitivity, and transient growth are each discussed. The spatial development of the vortex-wall interaction is shown to have a further stabilizing effect on the Crow instability due to a “lift-off” behavior. Despite these discoveries, it is still shown that amplitude growth on the order of 20% is possible and transient growth mechanisms might result in an order-of-magnitude of further growth if properly initiated. With these results in mind, an experiment is developed to isolate the streamwise vortex-wall interaction. Through the use of a vortex generating wing section and a suspended splitter plate, a stable interaction is created that agrees favorably in structure to the three-dimensional computations. A small synthetic jet actuator is mounted on the splitter plate below the vortex. Phase-locked stereo-PIV velocity data and surface pressure taps both show spatial amplification of the disturbance in a frequency range which agrees well with the prediction for the Crow instability. An analysis of the vortex response shows a primarily horizontal oscillation of the vortex column which strongly interacts with the secondary vortex structure that develops in the boundary layer.
Jeffrey Bons, Ph.D. (Advisor)
Mohammad Samimy, Ph.D. (Committee Member)
James Gregory, Ph.D. (Committee Member)
Jen-Ping Chen, Ph.D. (Committee Member)
168 p.
Aerospace Engineering; Fluid Dynamics
active flow control; vortex; linear stability; synthetic jet actuator; wind tunnel; particle image velocimetry; turbomachinery; low pressure turbine;

Recommended Citations

Citations

  • Benton, S. I. (2015). Capitalizing on Convective Instabilities in a Streamwise Vortex-Wall Interaction [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437664298

    APA Style (7th edition)

  • Benton, Stuart. Capitalizing on Convective Instabilities in a Streamwise Vortex-Wall Interaction. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1437664298.

    MLA Style (8th edition)

  • Benton, Stuart. "Capitalizing on Convective Instabilities in a Streamwise Vortex-Wall Interaction." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1437664298

    Chicago Manual of Style (17th edition)

osu1437664298
748
© 2015, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.