Measurement of shear-stress distribution by liquid-crystal coating

摘要

In the present paper, a method for measuring the shear-stress distribution over a solid surface in a fluid flow is studied with a use of shear-sensitive liquid crystal coating. The color response of the liquid crystal coating is calibrated against the various shear stress magnitudes and directions using an experimental test section of laminar channel flow. The measurement of shear stress distribution is carried out with a use of two color CCD cameras situated side by side. The color to shear stress transformation is conducted by the analysis with a use of relative hue as a calibration variable, which is a function of shear stress magnitudes and directions. The usefulness of this technique was confirmed by the measurement of shear stress distribution around a circular cylinder with small span.