Chemical recording of flow patterns

Abstract

Abstract The flow pattern of a fluid over a surface can be determined by treating the surface to form a reactive layer, entraining in the fluid a reagent compound which is capable of chemically changing the reactive layer, and then passing the fluid over the reactive layer which is to be examined. This method is illustrated by treating an aluminum surface of a blade member (such as that in a vacuum cleaner blower) or adjacent structural members to form a thin aluminum oxide film by anodic treatment. The microporous film which is formed is then impregnated with an organic dye. An air stream containing a reactive substance, such as acid vapors, is passed over the treated blade member. The acid vapors react with the dye and/or the oxide layer and produce a visible pattern upon the blade which is characteristic of the boundary layer flow of the air stream. An examination of the visible pattern is of assistance in determining the proper design and operating characteristics of the blade. The visible pattern may be formed or preserved by chemical post-treatment, such as etching to leach out dye from unreacted portions of the layer and to provide a more permanent record for subsequent use. Alternatively, the microporous aluminum oxide layer can be treated with a fluid stream containing a reactive substance to characteristically change the layer, followed by treatment with a dye to form the visible pattern of the boundary flow.

Inventors

• 👤 Richard Dotzer
• 👤 Winfried Plundrich

Bibliographic Details