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Base Pressures and Energy Separation in Transonic Turbine Blading

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conference contribution
posted on 07.11.2016, 10:19 by Jonathan P. Gostelow, Aldo Rona, A. Mahallati
This paper concerns unsteady near-wake flows on, and close to, the thick trailing edges of turbine blades, circular cylinders and similar bodies. Subsonic surface base pressures, and Eckert-Weise energy separation in the wake, are principal manifestations of the same phenomenon. Both are a direct result of von Kármán vortex shedding. The subsonic flow past a turbine blade having a thick trailing edge is still not well-predicted and this results from a lack of understanding of the flow past the trailing edge and into the wake. It is here argued that von Kármán vortex shedding is the principal cause of the subsonic base pressure deficit and the related energy separation in the wake. Parallels can be found in the behaviour of elastically-mounted circular cylinders and the caudal fin oscillation propelling fish. These should also affect supersonic flows although the physical causes are different. At supersonic speeds the trailing edge base pressure, and the energy separation in the downstream wake, exhibit different characteristics from the subsonic behavior and need to be treated differently. For supersonic flows, shock waves from a blade trailing edge may impinge on the adjacent suction surface adversely affecting the downstream boundary layer. Supersonic flows most often involve shock and expansion waves. Exotic vortex shedding also has an important role to play. In addition to experimental observation, the guidance of an analytical framework is needed. The eventual goal is accurate computational prediction for validation of computer models and prediction of flow behaviour.

History

Citation

20th Australasian Fluid Mechanics Conference, 2016

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Engineering

Source

20th Australasian Fluid Mechanics Conference, Perth, Australia

Version

AM (Accepted Manuscript)

Published in

20th Australasian Fluid Mechanics Conference

Publisher

Australasian Fluid Mechanics Society

isbn

978-1-74052-377-6

Acceptance date

14/08/2016

Available date

08/12/2016

Publisher version

http://people.eng.unimelb.edu.au/imarusic/proceedings/20/617 Paper.pdf

Editors

Ivey, G.;Jones, N.;Zhou, T.

Temporal coverage: start date

05/12/2016

Temporal coverage: end date

08/12/2016

Language

en