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Circulation Redistribution in Leading-edge Vortices on Rotating Wings
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- Author / Creator
- Giner-Morency, Clara
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This work presents an investigation into the circulation transport within an LEV on a rotating wing and its governing dynamics. These dynamics were used to produce a model for the computationally inexpensive prediction of circulation growth and distribution within an LEV. The test-case used in this study was performed on a thin flat plate in rotation at Re of Re=1000 and Re=2500.
The model conceptualizes the circulation transport as species transport, which means that fluid particles entering the leading-edge vortex shear-layer are conceptualized as vorticity-containing mass and are advected perfectly by the spanwise flow. The present work thus offers a study of the extent to which circulation is tied to mass, for some classes of three-dimensional flows. From the vorticity transport equation, a circulation balance is developed between a proposed circulation generation and the vorticity transport terms, such that only two unknows must be characterized by the model itself: the shear-layer velocity profile and the spanwise flow distribution. A shear-layer velocity relationship with the mass rate entering the LEV is suggested such that the modeller only needs to determine the shear-layer thickness. The spanwise flow distribution is characterized by a Bernoulli-derived equation such that both the rotational acceleration and the pressure gradient along the span are represented.
To verify the validity of the concept and the accuracy of the model predictions, the model is compared against experimental circulation measurements taken with PIV and show good agreement given an accurate spanwise flow. Moreover, the validity of both the shear-layer velocity profile model and the spanwise flow distribution approximation is investigated individually, again against experimental measurements. While the model showed sensitivity to the spanwise flow, the model showed to be insensitive to the value chosen by the modeller for the shear-layer thickness (the only unknown parameter).
Lastly, the present work offers an investigation of the vorticity annihilation and its effect on the modelled net circulation. The present work suggests that vorticity annihilation may be a local property and that the net circulation in the near-field of a wing may be determined from the leading-edge shear-layer alone. Hence, the present work argues that modelling the net circulation accounts for the vorticity annihilation mechanism acting locally without having to model the extra term.
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- Graduation date
- Fall 2022
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.