BOUNDARY LAYER-TRIPPING STUDIES ON CHARACTERISTICS OF NEAR-WAKE BEHIND A CAMBERlED AIRFOIL | ||
| ERJ. Engineering Research Journal | ||
| Article 8, Volume 22, Issue 3, October 1999, Pages 115-133 PDF (633.28 K) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/erjm.1999.72455 | ||
| Author | ||
| H.A. Abdalla | ||
| Department of Mechanical Power Engineering, Faculty of Engineering, Minufiya University, Shebin El-Kom, Egypt | ||
| Abstract | ||
| This paper presents an experimental study to the effects of boundary layer-tripping on the aerodynamic performance and the near-wake which generates immediately behind the trailing edge of NACA-2415 airfoil sections. The airfoil was tripped by separately placing two different trip wires near the leading edge as an artificial roughness to induce rapid transition. The tripped and untripped airfoil were tested at different angles of attack to indicate the effects of pressure gradient and streamline curvature on its aerodynamic performance and the wake development behind the airfoil sections. Measurements included lift and drag coefficients, static pressure distributions, and mean velocity profiles in the wake region at Reynolds numbers between 3.5~10~ and 1.92~10~. The results of this experimental investigation showed that the aerodynamic performance of the airfoil is sensitive to the tripping mechanism. The drag coefficient of the airfoil increases due to the distorted velocity profiles in the wake region caused by the boundary layer tripping. The boundary layer tripping did not affect strongly the wake velocity profiles in the case of negative angles of attack and the wake velocity distributions are symmetric. Asymmetric velocity profiles are observed in the wake region as the angle of attack increases, for both tripped and untripped airfoils. The results indicated also that, the pressure gradient and the separation location on airfoil surfaces significantly control the growth of the wake. The effect of the boundary layer tripping on the growth of the wake width, the decay of the maximum velocity defect and similarity of wake profiles are discussed. | ||
| Keywords | ||
| Cambered airfoil; Boundary layer tripping; Wake properties; Aerodynamic | ||
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