Experimental study of inertia-based passive flexibility of a heaving and pitching airfoil operating in the energy harvesting regime
| Autor: | Kiana Kamrani Fard, Firas Siala, James A. Liburdy |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Fluid Flow and Transfer Processes
Airfoil Physics Mechanical Engineering media_common.quotation_subject Flow (psychology) Computational Mechanics Mechanics Condensed Matter Physics Inertia 7. Clean energy 01 natural sciences 010305 fluids & plasmas Vortex Particle image velocimetry Mechanics of Materials 0103 physical sciences Trailing edge Pitching moment 010306 general physics Wind tunnel media_common |
| Zdroj: | Physics of Fluids. 32:017101 |
| ISSN: | 1089-7666 1070-6631 |
| DOI: | 10.1063/1.5119700 |
| Popis: | The effects of passive, inertia-induced surface flexibility at the leading and trailing edges of an oscillating airfoil energy harvester are investigated experimentally at reduced frequencies of k = fc/U∞ = 0.10, 0.14, and 0.18. Wind tunnel experiments are conducted using phase-resolved, two-component particle image velocimetry to understand the underlying flow physics, as well as to obtain force and pitching moment estimates using the vortex-impulse theory. Results are obtained for leading and trailing edge flexibility separately. It is shown that both forms of flexibility may alter the leading edge vortex inception and detachment time scales, as well as the growth rate of the circulation. In addition, surface flexibility may also trigger the generation of secondary vortical structures and suppress the formation of trailing edge vortices. The total energy harvesting efficiency is decomposed into contributions of heaving and pitching motions. Relative to the rigid airfoil, the flexible leading and trailing edge segments are shown to increase the energy harvesting efficiency by approximately 17% and 25%, respectively. However, both the flexible leading and trailing edge airfoils operate most efficiently at k = 0.18, whereas the peak efficiency of the rigid airfoil occurs at k = 0.14. It is shown that the flexible leading and trailing edge airfoils enhance the heaving contribution to the total efficiency at k = 0.18 and the negative contribution of the pitching motion at high reduced frequencies can be alleviated by using a flexible trailing edge. |
| Databáze: | OpenAIRE |
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