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Experiments to investigate lift production mechanisms on pitching flat plates

Published version
Peer-reviewed

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Type

Article

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Authors

Stevens, PRRJ 

Abstract

© 2016, The Author(s).Pitching flat plates are a useful simplification of flapping wings, and their study can provide useful insights into unsteady force generation. Non-circulatory and circulatory lift producing mechanisms for low Reynolds number pitching flat plates are investigated. A series of experiments are designed to measure forces and study the unsteady flowfield development. Two pitch axis positions are investigated, namely a leading edge and a mid-chord pitch axis. A novel PIV approach using twin laser lightsheets is shown to be effective at acquiring full field of view velocity data when an opaque wing model is used. Leading-edge vortex (LEV) circulations are extracted from velocity field data, using a Lamb–Oseen vortex fitting algorithm. LEV and trailing-edge vortex positions are also extracted. It is shown that the circulation of the LEV, as determined from PIV data, approximately matches the general trend of an unmodified Wagner function for a leading edge pitch axis and a modified Wagner function for a mid-chord pitch axis. Comparison of experimentally measured lift correlates well with the prediction of a reduced-order model for a LE pitch axis.

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Keywords

4012 Fluid Mechanics and Thermal Engineering, 40 Engineering, 4001 Aerospace Engineering

Journal Title

Experiments in Fluids

Conference Name

Journal ISSN

0723-4864
1432-1114

Volume Title

58

Publisher

Springer