Bullseye color schlieren flow visualization

In this variant of schlieren flow visualization a tricolored filter pattern made up of concentric rings is used instead of a knife edge at the cut-off plane. The method is particularly useful in combustion studies since it provides the range necessary to visualize flames while retaining the sensitivity necessary to detect fluid motion in the surrounding gasses. That utility is demonstrated in this paper in terms of basic principles and by application. Photographs presented include images of both premixed and diffusion flames in an unsteady swirling flow within a cylinder.