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Experimental study of the plunging motion with unsteady wind tunnel wall interference effects

Soltani, M. R ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1111/j.1747-1567.2010.00696.x
  3. Publisher: 2012
  4. Abstract:
  5. A series of experiments were carried out to investigate unsteady behavior of the flow field as well as the boundary layer of an airfoil oscillating in plunging-type motion in a subsonic wind tunnel. The measurements involved surface-mounted hot films complimented with surface pressure. In addition, wind tunnel wall pressure distribution was acquired to furnish a baseline for the wall interference corrections. The airfoil is the section of a 660-kW wind turbine blade. The experiments were conducted at a Reynolds number of 0.42 million, and over two reduced frequencies of k = 0.06 and 0.085, at prestall, nearstall, and poststall regions. The unsteady aerodynamic loads were calculated from the surface pressure measurements, 64 ports, along the chord for both upper and lower surfaces of the model. The plunging displacements were transformed into the equivalent angle of attack. The surface hot-film measurements provided information about the boundary-layer events. The boundary-layer transition occurred via a laminar separation bubble. Variations of the surface pressure coefficients and aerodynamic loads with the equivalent angle of attack showed strong sensitivity to the reduced frequency and the mean angles of attack. The wall pressure distribution was affected by the model oscillation especially the region underneath the model
  6. Keywords:
  7. Boundary-layer transition ; Experimental studies ; Hot-film measurement ; Laminar separation bubble ; Plunging ; Reduced frequency ; Subsonic wind tunnels ; Surface pressure coefficients ; Surface pressure measurements ; Surface pressures ; Surface-mounted hot films ; Unsteady aerodynamic load ; Unsteady wind tunnel ; Wall interference ; Wall-pressure distribution ; Wind tunnel walls ; Wind turbine blades ; Aerodynamic loads ; Airfoils ; Angle of attack ; Boundary layers ; Experiments ; Laminar flow ; Pressure distribution ; Reynolds number ; Sensitivity analysis ; Wind tunnels ; Interference suppression
  8. Source: Experimental Techniques ; Volume 36, Issue 5 , FEB , 2012 , Pages 30-45 ; 07328818 (ISSN)
  9. URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1747-1567.2010.00696.x/abstract