Experimental Investigation of Reduced Frequency Effects on the Wake of an Airfoil in Plunging Motion

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Dallali, Maryam | 2009

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Type of Document: M.Sc. Thesis
Language: Farsi
Document No: 40953 (45)
University: Sharif University of Technology
Department: Aerospace Engineering
Advisor(s): Soltani, Mohammad Reza
Abstract:
Wake aerodynamic of plunging airfoils have received less attention than the other unsteady phenomena. An experimental investigation was carried out to study the unsteady characteristics of flow field behind a model of a plunging airfoil in various conditions. The model has 0.25cm chord and is the 16m section of a 660kW wind turbine blade. All tests were conducted in the subsonic closed circuit wind tunnel in Iran. Invariable parameters were plunging amplitude, mean angle of attack and plunging frequency. The Wakes of plunging airfoil can be characterized as drag-producing, neutral, or thrust-producing .Our preliminary results show that the structure of vortex in the wake for the plunging airfoil was highly affected by the reduced frequency and plunging amplitude value. Mean velocity profiles show that the momentum loss in the wake is decreased as the reduced frequency increase.
Keywords:
Unsteady Flow ; Wakes ; Reduced Frequency ; Hysteresis ; Plunging