Suppression of Dynamic Stall with a Leading-Edge Slat on a VR-7 Airfoil
Abstract
The VR-7 airfoil was experimentally studied with and without a leading-edge slat at fixed angles of attack from 0 deg to 30 deg at Re = 200,000 and for unsteady pitching motions described by a = am + 10 deg sin(wt). The models were two dimensional, and the test was performed in a water tunnel at Ames Research Center. The unsteady conditions ranged over Re = 100,000 - 250, 000, k = 0.001 0.2, and am = 10 deg - 20 deg. Unsteady lift, drag, and pitching- moment measurements were obtained along with fluorescent-dye flow visualizations. The addition of the slat was found to delay the static-drag and static-moment stall by about 5 deg and to eliminate completely the development of a dynamic-stall vortex during unsteady motions that reached angles as high as 25 deg. In all of the unsteady cases studied, the slat caused a significant reduction in the force and moment hysteresis amplitudes. The reduced frequency was found to have the greatest effect on the results, whereas the Reynolds number had little effect on the behavior of either the basic or the slatted airfoil. The slat caused a slight drag penalty at low angles of attack, but generally increased the lift/drag ratio when averaged over the full cycle of oscillation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1993
- Accession Number
- ADA271988
Entities
People
- C. Tung
- K. W. Mcalister
Organizations
- National Aeronautics and Space Administration