skip to main content

Title: Liquid crystals for unsteady surface shear stress visualization

Oscillating airfoil experiments were conducted to test the frequency response of thermochromic liquid crystal coatings to unsteady surface shear stresses under isothermal-flow conditions. The model was an NACA-0015 airfoil, exposed to an incompressible flow at a freestream Reynolds number (based on chord) of 1.14 x 10/sup 6/. Angle-of-attack forcing functions were sine waves of amplitude +- 10/degree/ about each of three mean angles of attack: 0/degree/, 10/degree/, and 20/degree/. Frequencies of oscillation were 0.2, 0.6 and 1.2 hertz, corresponding to reduced frequencies of 0.0055, 0.0164 and 0.0328. Data acquisition was accomplished by video recording. Observations showed the liquid crystal technique capable of visualizing high surface shear stress zones over the stated dynamic range in a continuous and reversible manner. 11 refs.
Authors:
Publication Date:
OSTI Identifier:
5025923
Report Number(s):
SAND-88-1360C; CONF-880716-3
ON: DE88010570
DOE Contract Number:
AC04-76DP00789
Resource Type:
Conference
Resource Relation:
Conference: 1. national fluid dynamics congress, Cincinnati, OH, USA, 24 Jul 1988
Research Org:
Sandia National Labs., Albuquerque, NM (USA)
Country of Publication:
United States
Language:
English
Subject:
17 WIND ENERGY; LIQUID CRYSTALS; OPTICAL PROPERTIES; USES; STRESSES; MEASURING METHODS; TURBINE BLADES; MECHANICAL VIBRATIONS; WIND TURBINES; BOUNDARY LAYERS; SHEAR; CRYSTALS; FLUIDS; LAYERS; LIQUIDS; MACHINERY; PHYSICAL PROPERTIES; TURBINES; TURBOMACHINERY 170602* -- Wind Energy Engineering-- Turbine Design & Operation