ABSTRACT
This chapter focuses primarily on flow visualization undertaken during routine testing in wind tunnels and related aerospace facilities. General information on wind tunnel testing and the applications of flow visualization therein is widely available. Both the applications and methods employed can be grouped according to flow regimes as follows. Surface flow visualization by way of pigmented or fluorescent oil flow is routinely carried out in wind tunnel tests of aerospace vehicles and components. Many examples can be found in the literature. The resulting patterns are photographed and examined for evidence of phenomena of interest, such as flow separation, boundary layer transition, etc. Optical instrumentation is available at most high-speed wind tunnel facilities in the form of a Z-type schlieren system. Such a system can produce either schlieren or shadowgram flow images and can be modified for holographic interferometry. Holographic interferometry like its predecessor, Mach—Zehnder interferometry, is somewhat beyond the class of rough-and-ready wind tunnel flow visualization techniques.
