Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5017390 | Journal of Fluids and Structures | 2017 | 12 Pages |
Abstract
The dynamics of a two-dimensional vortex interacting with a flat plate at different angles of attack α is analysed using potential flow theory based on conformal mapping varying the nondimensional separation distance hâc of the upstream incoming vortex to the plate (c is the chord length of the plate) and the vortex intensity Îl. Transient lift forces measured in a wind tunnel are also compared with the potential theory results for a given Îl and several values of hâc and α. For the Reynolds number considered in the experiments (about 25 000) it is found that the potential theory predicts reasonably well the transient fluctuation in the lift force provided that the separation distance is not too close to the critical one hââc at which the vortex trajectory given by the potential theory bifurcates. We find that the separation distance generating the highest induced lift is around this critical value hââc, which, according to the potential theory, is displaced about â2.3(1â0.07|Îl|1â2)α in relation to the zero angle of attack for the same Îl. Potential theory also predicts that the maximum peak of the lift fluctuation depends on α only through the relative separation |hâhâ|âc, and that the maximum lift is substantially larger when a clockwise vortex passes below the plate than when it passes above the plate, for the same vortex intensity Îl and relative separation distance. The opposite happens for a counter-clockwise vortex. This asymmetry in the maximum lift fluctuation increases slightly with |Îl|, approaching a ratio of almost two for large |Îl|.
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Physical Sciences and Engineering
Engineering
Mechanical Engineering
Authors
J. Alaminos-Quesada, R. Fernandez-Feria,