Observations of dynamic stall phenomena on an oscillating airfoil with shear-stress-sensitive liquid crystal coatings

Conference · Sun Jan 01 00:00:00 EST 1989

OSTI ID:7020647

Reda, D C

Oscillating airfoil experiments were conducted using shear-stress- sensitive/temperature-insensitive liquid crystal coatings in order to investigate unsteady fluid physics associated with the dynamic-stall process. Laser-light-sheet/smoke-particle flow visualization and surface-mounted micro-tufts were also employed to complement the liquid crystal technique. Experiments were conducted under incompressible flow conditions at a freestream Reynolds number (based on chord) of {approximately}10{sup 6}. Angle-of-attack oscillations of {plus minus}19{degree} about 0{degree}, at several discrete frequencies, were used to induce the unsteady flows. Boundary layer transition and turbulent separation locations were seen to undergo extensive and rapid movements with changing angle of attack, particularly on the airfoil lee surface. Progression of turbulent separation to the immediate vicinity of the leading edge was observed (via the liquid crystal technique) to result in large-scale, high-frequency fluctuations in the surface shear stress distribution. Comparisons of transition and turbulent separation measurements with Eppler code predictions indicated that the empirically-based viscous flow modeling used in this design tool requires updates. 19 refs., 8 figs., 1 tab.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: DOE/CE
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 7020647
• Report Number(s): SAND-89-0874C; CONF-900930-1; ON: DE89013932
• Resource Relation: Conference: 17. International Council of Aeronautical Sciences (ICAS) meeting, Stockholm (Sweden), 9-14 Sep 1990
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
AIRFOILS
AERODYNAMICS
AIRCRAFT COMPONENTS
FLOW MODELS
FLUID FLOW
LIQUID CRYSTALS
REYNOLDS NUMBER
TURBULENT FLOW
CRYSTALS
FLUID MECHANICS
FLUIDS
LIQUIDS
MATHEMATICAL MODELS
MECHANICS
420200* - Engineering- Facilities
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320201 - Energy Conservation
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& Utilization- Transportation- Air & Aerospace