Method for laminar boundary layer transition visualization in flight

US4774835A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• Bruce J. Holmes · Williamsburg, US
• Peter Gall · Uttenreuth, DE

Key dates

• Filing date: Nov 13, 1986
• Grant date: Oct 4, 1988
• Expiry date: Nov 13, 2006

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S116/43
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Disclosed is a method of visualizing laminar to turbulent boundary layer transition, shock location, and laminar separation bubbles around a test surface. A liquid crystal coating is formulated using an unencapsulated liquid crystal operable in a temperature bandwidth compatible with the temperature environment around the test surface. The liquid crystal coating is applied to the test surface, which is preferably pre-treated by painting with a flat black paint to achieve a deep matte coating, after which the surface is subjected to a liquid or gas flow. Color change in the liquid crystal coating is produced in response to differences in relative shear stress within the boundary layer around the test surface.