Accession Number : ADA268649


Title :   Transition Effects on Compressible Dynamic Stall of Transiently Pitching Airfoils


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


Personal Author(s) : Wilder, M C ; Chandrasekhara, M S ; Carr, L W


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a268649.pdf


Report Date : Jul 1993


Pagination or Media Count : 15


Abstract : Experimental results and analysis of the effects of boundary layer tripping on dynamic stall of a transiently pitching airfoil are presented. At low Mach numbers, the tripped airfoil exhibits qualitative similarity with the behavior of the untripped airfoil. However, the local supersonic flow at Mach numbers greater than 0.3 is significantly modified by the trip leading to vastly different shock/boundary layer interactions, dynamic stall onset and vortex formation angles. The formation of the laminar separation bubble is found to have a favorable influence in delaying dynamic stall on the untripped airfoil flow. In both Mach number regimes, the tripped flow actually stalls at slightly lower angles of attack. Further experimentation with three trips on an oscillating airfoil showed that the dynamic stall process is very sensitive to the state of the turbulence in the boundary layer. This sensitivity points to a need for finer turbulence modeling techniques for use in dynamic stall computations.


Descriptors :   *DYNAMICS , *BOUNDARY LAYER , *AERODYNAMIC CHARACTERISTICS , *STALLING , ANGLES , COMPUTATIONS , TURBULENCE , SHOCK , BEHAVIOR , NUMBERS , SUPERSONIC FLOW , MACH NUMBER , FLOW , SEPARATION , BUBBLES , SENSITIVITY , AIRFOILS , ATTACK , LAYERS , INTERACTIONS


Subject Categories : Aerodynamics


Distribution Statement : APPROVED FOR PUBLIC RELEASE