Ultrafast-Response Anodized-Aluminum Pressure-Sensitive Paints for Unsteady Flow Measurement

To apply pressure-sensitive paint (PSP) to unsteady shock-wave phenomena such as shock–obstacle interactions in shock-tube experiments, anodized-aluminum PSP (AA-PSP) with ultrafast response was fabricated and its response time to a step pressure change was evaluated by using a shock tube. Phosphoric acid was used as electrolyte in the anodization process, and the anodic alumina with pore diameter as large as 160 nm was successfully fabricated. This improved AA-PSP achieved a response with the time constant of 0.35  μs. This AA-PSP was applied to interactions of a moving shock wave with a circular cylinder. The results show that the improved AA-PSP can visualize the shock reflections and the shock diffractions with the ever-highest spatial and temporal resolution.