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Experimental Investigation of the Roughness Effects on the Pressure Distribution and Stationary Crossflow Instability over a Swept wing

Damghani, Hamid | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42010 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Soltani, Mohammad Reza
  7. Abstract:

  8. Wind tunnel experiments are conducted to evaluate surface pressure distribution over a semi span swept wing with sweep angle of 33 degrees. The wing section has a laminar flow airfoil similar to that of NACA 6-series airfoils. The tests were conducted at speeds ranging from 50 to 70m/s with and without surface roughness. Surface static pressure was measured on the wing upper surface at three different chordwise rows located at the inboard station, (section 1, 2y/b=0.2), middle station, (section 2, 2y/b=0.43), and outboard station, (section 3, 2y/b=0.78). The differences between pressure distributions on the three sections of the wing were studied and the experimental results showed that roughness elements except at the inboard station do not influence the pressure distribution significantly. On the other hand, pressure-time signals acquired from pressure orifices over the wing upper surface maybe analyzed by spectral analyses. Determining zero frequency amplitude and its variations by roughness elements was the main object, because it plays an important role in the swept wings flow. So zero frequency distribution at three different chordwise rows was obtained with and without surface roughness. Spectral analysis results specified the zero frequency amplification area over the three considered stations. Also, results showed that roughness elements amplified zero frequency amplitude over the swept wings. Roughness elements were placed at X/c=0.05 and parallel to the wing L.E.

  9. Keywords:
  10. Pressure Distribution ; Experimental Results ; Frequency Analysis ; Roughness ; Swept Wing ; Zero Frequency Instability

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