Oscillating Flap Excitation Control of a Dynamic Stall Seperation Flow Over a Wing

碩士 === 國立成功大學 === 航空太空工程學系 === 83 === The active control of separated and unsteady flow over NACA 633-018 cross section airfoil at high angle of attack is studied experimentally by means of a leading-edged periodic oscillating flap located...

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Bibliographic Details
Main Authors: Shih-Yu Pan, 潘時瑜
Other Authors: Fei-Bin Hsiao
Format: Others
Language:en_US
Published: 1995
Online Access:http://ndltd.ncl.edu.tw/handle/06526828570004776672
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Summary:碩士 === 國立成功大學 === 航空太空工程學系 === 83 === The active control of separated and unsteady flow over NACA 633-018 cross section airfoil at high angle of attack is studied experimentally by means of a leading-edged periodic oscillating flap located near the separation point. Theparameters here investigated include the forcing frequency of the flap, the angles of attack of the airfoil and the Reynolds number herein is 1.9 × 10^5. The contents of this experiment include the comparisons of the pressure distributions along the wing with and without excitation, the frequency spectrum analysis of the fluctuation pressure along the upper surface of the airfoil, the dynamic variations of the aerodynamic properties with the flap oscillating and the vortex convection speed along the airfoil. The results indicate that the periodic excitation indeed have the ability to synchronize and enhance the strength of the shedding vortices over the airfoil when the oscillating frequency is close to the vortex shedding frequency in the wake region. The enhanced shedding vortices increase the adverse flow strongly and lower the pressure distribution over the upper surface. Thus, the excitation causes the increases and the periodic variations both in lift and drag. Besides, from the variations of the fluctuation pressure along the upper surface of the airfoil, we can calculate the ratio of the vortex convection speed and the freestream speed is from 0.67 to 0.87.