Photographing flow fields and heat-transfer patterns in color simultaneously.

A color-schlieren technique is described that combines the flow-field shock shapes and the phase-change coating to give a very descriptive account of aerodynamic heating. This technique employs, in addition to the conventional schlieren system, a temperature-sensitive material as a thin surface coating that undergoes a visible phase change from opaque solid to clear liquid at a known temperature. The resulting pictures can lead to a better understanding of shock/boundary layer interactions, as shown with the aid of a specific example.