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