A Novel, Portable, Projection, Focusing Schlieren System

The schlieren technique has been used for flow diagnostics in wind tunnels since the beginning of aerospace research due to its ability to make airflows?especially shock waves and turbulence?visible. This proposal describes a novel type of schlieren system that would increase efficiency, capability, and productivity for ground test facilities. The concept and the availability of state-of-the-art components make the system more portable, easier to align, and more versatile than existing systems. A major drawback of current schlieren systems, and one that has restricted their widespread commercial use, is that they require exact alignment between a pair of widely separated mirrors or grids, which takes time and limits portability, and costs are prohibitive for most such applications. This problem is partially relaxed by focusing schlieren methods. The proposed concept incorporates features of existing schlieren systems while removing the primary limitations. All of the elements that require precise alignment are contained within a camera body and can be relatively inexpensive. Very large fields of view are made possible. This is advantageous in wind tunnel facilities, since experiments are frequently installed only to be torn down shortly afterwards.