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Analysis of Unsteady Flow Field around a Pitching Finite Wing

Kavianpour, Sina | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53577 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Farahani, Mohammad
  7. Abstract:
  8. The characteristics of unsteady flow field around a low-aspect-ratio pitching wing with an airfoil section used in horizontal axis wind turbine are investigated at Reynolds number 2.8×105 and Mach number 0.06. The major objective of this study was to investigate the effects of reduced frequency, oscillating amplitude, mean angle of attack and 3D effects on aerodynamic coefficients. Using aerodynamic coefficients, the unsteady aerodynamics in pre-, near-, and post-static stall regions are analyzed and the results are validated with the corresponding experimental data. The two-dimensional simulation results demonstrate the significant effects of reduced frequency, mean angle of attack and oscillating amplitude on stall delay, maximum lift and drag coefficients and hysteresis loops width. Increasing the reduced frequency in post-stall region causes the increase in slope of the lift coefficient in upstroke motion. This leads to achieve a higher maximum lift coefficient at higher angle of attack. To investigate the effects of wingtip vortices on unsteady aerodynamic coefficients, Three-dimensional simulations is conducted in pre-static stall region. The difference between the values of the aerodynamic coefficients at tip section compared to root and middle sections of the wing indicates the important role of wingtip vortices in determining the aerodynamic coefficients
  9. Keywords:
  10. Reduced Frequency ; Pitching Oscillation ; Unsteady Flow ; Hysteresis Ring ; Attack Angle ; Oscillation Amplitude ; Attack Mean Angle ; Finite Wing

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