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| Portable Color Schlieren System |
| Schlieren optical systems are commonly used by researchers to visualize an air flow with changes in density that cannot easily be seen by the naked eye by detecting refractive differences in the light passing through the area of interest. Along with the visual aspects of a schlieren system, valuable information can be obtained to either confirm theoretical concepts or to explore flow characteristics. The ARC contains a Z-configuration schlieren system that is both portable and simple to assemble for use with several wind tunnels. Two sets of 6" mirrors and one set of 16" mirrors are available for use. Alignment, often the most time-consuming task with schlieren systems, can be completed rapidly with the use of a mobile laser alignment system connected to the mirrors. A knife edge is typically used with the system to produce black-and-white images with high contrast. A variety of color filters have been developed to replace the knife edge. A picture and movie are shown below where the system is placed around the 6"x6" supersonic wind tunnel. |
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| The picture on the left shows a microvortex generator test and the movie shows the starting process of the wind tunnel. |
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| Below, pictures and movies show results of experiments with several types of multi-color schlieren filters and the Mach 2 freejet supersonic nozzle. The supersonic nozzle is about 2.5" high and has a 0.6" width. The color schlieren images show the underexpanded, perfectly expanded, and overexpanded states among other non-ideal behavior due to viscous effects. |
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