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Frequency Analysis of the Wake of an Oscillating Airfoil

Shariloo, Koosha | 2023

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 56215 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Ebrahimi, Abbas
  7. Abstract:
  8. Understanding the physics of unsteady flow is very important due to various applications. Axial compressors, turbines, helicopter blades, and energy harvesters are the essential applications of this problem. An airfoil under pitching oscillation is one of the common cases in unsteady aerodynamics, and several characteristics of the flow around it have been investigated up to now. The frequency analysis of the wake flow for pitching airfoils has received less attention. In this research, experimental tests have been carried out for symmetric airfoil NACA 0012 under pitching oscillation in low Reynolds flow (6×104) and before the airfoil stall condition. The experiments were carried out in the Experimental Aerodynamics Laboratory of the Faculty of New Sciences and Technologies of University of Tehran. The oscillation amplitude in both tests was 6 degrees, and the angle of attack of installation for the first and second cases was 0 and 3 degrees, respectively. The effect of reduced frequency on the lift coefficient and pressure distribution on the airfoil surface has been studied. Increasing the reduced frequency causes acceleration and a decrease in the size of the laminar separation bubble. Frequency analysis for surface pressure signal and wake flow was performed by continuous wavelet transform. The results of the frequency analysis of the wake flow show the reduction of the wake width due to the increase in the reduced frequency. The contour of the wavelet coefficients shows the impact of two and three times the frequency of the pitching motion in the wake flow, which decreases with the increase in the frequency of their contribution to the magnitude
  9. Keywords:
  10. Unsteady Aerodynamic ; Pitching Motion ; Experimental Aerodynamics ; Frequency Analysis ; Low Reynolds Number ; Airfoil ; Pitching Oscillation

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