Accession Number : ADA274150

Title :   Effect of an Extendable Slat on the Stall Behavior of a VR-12 Airfoil.

Descriptive Note : Technical paper,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : De Hugues, P. P. ; McAlister, K. W. ; Tung, C.

Report Date : SEP 1993

Pagination or Media Count : 66

Abstract : Experimental and computational tests were performed on a VR- 1 2 airfoil to determine if the dynamic-stall behavior that normally accompanies high-angle pitch oscillations could be modified by segmenting the forward portion of the airfoil and extending it ahead of the main element. In the extended position the configuration would appear as an airfoil with a leading-edge slat, and in the retracted position it would appear as a conventional VR-12 airfoil. The calculations were obtained from a numerical code that models the vorticity transport equation for an incompressible fluid. These results were compared with test data from the water tunnel facility of the Aeroflight-dynamics Directorate at Ames Research Center. Steady and unsteady flows around both airfoils were examined at angles of attack between 0 deg and 30 deg. The Reynolds number was fixed at 200,000 and the unsteady pitch oscillations followed a sinusoidal motion described by alpha = alpha (m) + 10 deg sin(wt). The mean angle (alpha m)was varied from 10 deg to 20 deg and the reduced frequency from 0.05 to 0.20. The results from the experiment and the calculations show that the extended-slat VR-1 2 airfoil experiences a delay in both static and dynamic stall not experienced by the basic VR- 12 airfoil. Airfoil stall, Dynamic stall, Leading-edge slat, High-lift device.

Descriptors :   *AIRFOILS, *BEHAVIOR, *LEADING EDGES, *STALL WARNING INDICATORS, *STALLING, ANGLES, ATTACK, BOLTZMANN EQUATION, CONFIGURATIONS, DELAY, DYNAMICS, EDGES, EQUATIONS, FACILITIES, FLUIDS, FREQUENCY, HIGH ANGLES, HIGH LIFT, LIFT, MODELS, MOTION, NUMBERS, OSCILLATION, REYNOLDS NUMBER, STATICS, TEST AND EVALUATION, TRANSPORT, TUNNELS, WATER, WATER TUNNELS.

Subject Categories : Military Aircraft Operations
      Flight Control and Instrumentation

Distribution Statement : APPROVED FOR PUBLIC RELEASE