NONDISTURBING TRACER TECHNIQUE FOR QUANTITATIVE MEASUREMENTS IN TURBULENT FLOW

A new nondisturbing flow visualization technique, in which a photochromic dye is dissolved in the test fluid and irradiated with ultraviolet light to produce a colored trace, has been extended to make quantitative measurements in the entire cross section of a tube in both laminar and turbulent flow. A giant-pulse ruby laser with frequency doubler was used to induce the tautomeric reaction in the dye, and quantitative measurements were made from high-speed movies. The technique and experimental conditions required to produce a long, thin trace are described. Mean velocity profiles proposed by Spalding and others have been confirmed; mean shear stresses at the wall agree very well with those calculated from the friction factor relation of Blasius. © 1969, American Chemical Society. All rights reserved.