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Experimental study of the boundary layer over an airfoil in plunging motion

Rasi Marzabadi, F ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1007/s10409-012-0039-1
  3. Abstract:
  4. This is an experimental study on the boundary layer over an airfoil under steady and unsteady conditions. It specifically deals with the effect of plunging oscillation on the laminar/turbulent characteristics of the boundary layer. The wind tunnel measurements involved surface-mounted hot-film sensors and boundary-layer rake. The experiments were conducted at Reynolds numbers of 0.42×10 6 to 0.84 × 10 6 and the reduced frequency was varied from 0.01 to 0.11. The results of the quasi-wall-shear stress as well as the boundary layer velocity profiles provided important information about the state of the boundary layer over the suction surface of the airfoil in both static and dynamic cases. For the static tests, boundary layer transition occurred through a laminar separation bubble. By increasing the angle of attack, disturbances and the transition location moved toward the leading edge. For the dynamic tests, earlier transition occurred with increasing rather than decreasing effective angle of attack. The mean angle of attack and the oscillating parameters significantly affected the state of the boundary layer. By increasing the reduced frequency, the boundary layer transition was promoted to the upstroke portion of the equivalent angle of attack, but the quasi skin friction coefficient was decreased
  5. Keywords:
  6. Airfoil ; Boundary layer ; Wind tunnel ; Boundary layer transitions ; Boundary layer velocity ; Dynamic tests ; Experimental studies ; Laminar separation bubble ; Leading edge ; Plunging ; Reduced frequency ; Skin friction coefficient ; Static and dynamic ; Static tests ; Suction surfaces ; Transition locations ; Unsteady ; Unsteady conditions ; Wind tunnel measurements ; Angle of attack ; Boundary layer flow ; Boundary layers ; Laminar flow ; Reynolds number ; Wind tunnels ; Airfoils
  7. Source: Acta Mechanica Sinica/Lixue Xuebao ; Volume 28, Issue 2 , 2012 , Pages 372-384 ; 05677718 (ISSN)
  8. URL: http://link.springer.com/article/10.1007%2Fs10409-012-0039-1