Simultaneous Measurements of Pressure and Velocity in Gas Phase Flows via Pressure-Sensitive Microspheres

Airborne, pressure-sensitive polystyrene microspheres (PSBeads) were used to obtain simultaneous pressure and velocity measurements of gas phase flows. The PSBeads, 2.5 $\mu$m in diameter, contained a pressure-sensitive luminophor (platinum octaethylporphyrin) that was incorporated into the polymer microspheres during the polymerization process. Pressure measurements of airborne PSBeads were made using the modified Rapid Lifetime Determination method, a technique that allows for simultaneous velocity measurements using a single CCD. Work will be presented showing the titration of airborne PSBeads in gases ranging from 0 to 21\% oxygen. In addition, pressure and velocity measurements of the gas phase flow within sealed syringe will also be shown. Initial studies suggest that pressure variations as small as 10\% can be detected by the airborne PSBeads without the benefit of signal averaging.