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Investigation of the Effects of Reduced Frequency and Mean Angle of Attack on the Surface Pressure of a Supercritical Airfoil in Pitching Oscillation

Shokri, Hossein | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47733 (45)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza
  7. Abstract:
  8. Supercritical airfoils have been designed for transonic flow, however due to different flight conditions, the airfoil behavior during take-off and landing of the aircraft in subsonic flow regime must be known. Experimental and numerical information derived from supercritical airfoils are less than those of conventional airfoils. Because of the special geometry of supercritical airfoils and different phenomena that occurs through flow, using such airfoils even in steady states requires precise study/analysis of the flow. Therefore, one could benefit from experimental tests to better understand flow phenomena. The objective of the present research is the study effect of mean angle of attack and reduced frequency on the pressure distribution around an airfoil oscillating in pitch. The model is a section of NACA series supercritical airfoil. All tests were conducted in a 0.8×0.8 m2 subsonic wind tunnel. The Oscillation motion was produced by sinusoidally oscillating system over a range of reduced frequency from 0.001 to 0.03. Tests were carried out at a Reynolds number being 0.87×106 at various angles of attack before dynamical stall. The model was pitched around its quarter-chord. Different pitch rate, initial angle of attack and oscillation amplitudes were applied to determine their effects on the surface pressure distributions. It was found that there exists significant differences in the flow pattern over supercritical airfoils when compared to the conventional airfoils. In addition, the outputs of this research were used to obtain the maximum lift coefficient. Moreover, the results were compared to numerical and subsonic wind tunnel results in Imam Hossein University
  9. Keywords:
  10. Unsteady Aerodynamic ; Reduced Frequency ; Pitching Oscillation ; Supercritical Airfoil ; Attack Angle

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