Accession Number:

ADA218227

Title:

Use of Liquid Crystals for Qualitative and Quantitative 2-D Studies of Transition and Skin Friction

Descriptive Note:

Technical memo.

Corporate Author:

ROYAL AEROSPACE ESTABLISHMENT FARNBOROUGH (UNITED KINGDOM)

Personal Author(s):

Report Date:

1989-06-01

Pagination or Media Count:

36.0

Abstract:

The exploitation of the properties of liquid crystals for use in wind tunnels to visualize transition and to measure skin friction is described. The effectiveness of a transition band to trip the laminar boundary layer on a swept wing is demonstrated by the growth of turbulent wedges with Reynolds number. The ability to liquid crystals to reveal intricate surface flow structure is clearly shown by subtle changes of colour on an unswept rectangular wing when subjected to the combined effects of transition, separation, reattachment and a normal shock. The time response of liquid crystals to changes in shear stress is illustrated by the shock pattern on the model surface which was seen to be oscillating. A method involving the digitisation of the video image into its three component colours has the potential for measuring skin friction in great detail. This involves using relationships firstly correlating the component colours with wavelength and secondly correlating shear stress with wavelength. Great Britain.

Subject Categories:

  • Aerodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE