Visualization of boundary layer transition zone movement on oscillating airfoils with shear-sensitive liquid-crystal coatings

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

OSTI ID:5499582

Reda, D. C.; Butterfield, C. P. ^[1]

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1. Oak Ridge National Lab., TN (USA)

Oscillating, and post-stall static, airfoil experiments were conducted to test the frequency response of shear-stress-sensitive/temperature-insensitive liquid crystal coatings. The airfoil was a natural-laminar-flow profile designed specifically for vertical axis wind turbine applications (the SAND 0018/50). A full-span model of this contour was exposed to incompressible flows at a freestream Reynolds number (based on chord) of 1.0 {times} 10{sup 6}. Angle-of-attack forcing function was a sine wave of amplitude {plus minus} 10{degree} about a mean angle of 0{degree}. Frequencies of oscillation were 0.2, 0.6 and 1.2 hertz, corresponding to reduced frequencies of 0.006, 0.018 and 0.037. Post-stall static experiments were conducted at a fixed angle of attack of 14{degree}, a condition that yielded unsteady leading-edge separation phenomena. Data acquisition was accomplished by video recording. Observations of boundary layer transition zone movement and unsteady leading-edge separation showed the liquid crystal technique capable of visualizing transient surface shear stress events over the stated dynamic range in a continuous and reversible manner, with a color-change response time of less than 0.03 seconds (the framing rate of standard video equipment). 14 refs., 3 figs.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: DOE/CE
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 5499582
• Report Number(s): SAND-88-3231C; CONF-891208-2; ON: DE89009570
• Resource Relation: Conference: Winter annual meeting of the American Society of Mechanical Engineers, San Francisco, CA (USA), 10-15 Dec 1989
• Country of Publication: United States
• Language: English

Related Subjects

17 WIND ENERGY
42 ENGINEERING
TURBINE BLADES
SHEAR PROPERTIES
AIRFOILS
COATINGS
LIQUID CRYSTALS
MEASURING METHODS
STRESSES
VERTICAL AXIS TURBINES
WIND TURBINES
CRYSTALS
FLUIDS
LIQUIDS
MACHINERY
MECHANICAL PROPERTIES
TURBINES
TURBOMACHINERY
170602* - Wind Energy Engineering- Turbine Design & Operation
420200 - Engineering- Facilities
Equipment
& Techniques