Transition effects on compressible dynamic stall of transiently pitching airfoilsExperimental 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.
Document ID
19930064174
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Wilder, M. C. (U.S. Navy-NASA Joint Inst. of Aeronautics; MCAT Inst. San Jose, CA, United States)
Chandrasekhara, M. S. (U.S. Navy-NASA Joint Inst. of Aeronautics; U.S. Naval Postgraduate School Monterey, CA, United States)
Carr, L. W. (U.S. Army, Aeroflightdynamics Directorate; NASA, Ames Research Center Moffett Field, CA, United States)