A learning-based approach for solving shear stress vector distribution from shear-sensitive liquid crystal coating images

The shear-sensitive liquid crystal coating (SSLCC) technique is investigated in the high-speed jet flow of a micro-wind-tunnel. An approach to measure surface shear stress vector distribution using the SSLCC technique is established, where six synchronous cameras are used to record the coating color at different circumferential view angles. Spatial wall shear stress vector distributions on the test surface are obtained at different velocities. The results are encouraging and demonstrate the great potential of the SSLCC technique in high-speed wind-tunnel measurement.

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Measurement of surface shear stress vectors using liquid crystal coatings

AIAA Journal ◽

10.2514/3.12146 ◽

1994 ◽

Vol 32 (8) ◽

pp. 1576-1582 ◽

Cited By ~ 33

Author(s):

Daniel C. Reda ◽

Joseph J. Muratore

Keyword(s):

Shear Stress ◽

Liquid Crystal ◽

Surface Shear Stress ◽

Surface Shear

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Unidirectional Homogenous Alignment of Smectic Liquid Crystal under Shear Stress

Ferroelectrics ◽

10.1080/00150193.2012.684634 ◽

2012 ◽

Vol 431 (1) ◽

pp. 74-80 ◽

Cited By ~ 3

Author(s):

Jaeki Kim ◽

Hiroyuki Yoshida ◽

Hiroshi Moritake ◽

Masanori Ozaki

Keyword(s):

Shear Stress ◽

Liquid Crystal ◽

Smectic Liquid Crystal

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Measurement of the Wall Shear Stress With Sublayer Thin Plate of Thermochromic Liquid Crystal

Volume 1A: Symposia, Part 2 ◽

10.1115/ajkfluids2015-25474 ◽

2015 ◽

Author(s):

Takashi Kodama ◽

Shinsuke Mochizuki

Keyword(s):

Shear Stress ◽

Liquid Crystal ◽

Friction Coefficient ◽

Wall Shear Stress ◽

Skin Friction ◽

Channel Flow ◽

Skin Friction Coefficient ◽

Local Skin ◽

Local Skin Friction ◽

Wall Shear

New optical method for measurement of the local wall shear stress has been developed by using thermo-chromic liquid crystal temperature measurement based on hue [1], [2] of the camera view. The flow field is the fully developed turbulent channel flow. Thin film made of thermo-chromic liquid crystal is placed on the wall. A rectangular shaped obstacle is glued on the film. The obstacle is within a region of buffer layer with height from the wall. Temperature of the film and the obstacle are slightly raised by a heater below the wall. The air flow makes non-uniform temperature distribution and non-uniform color distribution appears on the surface of the film. Relations between hue and local skin friction coefficient were examined in a turbulent air channel flow. It is indicated that a certain hue of a point is varying linearly against the corresponding local skin friction coefficient.

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