Development and Characterization of Pressure-Sensitive Microbeads for Simultaneous Barometry and Velocimetry for Fluid Dynamic Applications

Abstract

The use of luminescent dyes to measure pressures and temperatures on surfaces using Pressure Sensitive Paint (PSP) and Temperature-Sensitive Paint (TSP) is a well-established methodology. New technology has allowed for microbeads to be loaded with pressure and/or temperature sensitive dyes. These microbeads can be seeded into flow fields in order to measure the pressure and/or temperature fields in the fluid flow. In addition, the microbeads act as tracer particles to the fluid velocity and therefore, standard PIV techniques can be applied to quantify the velocity of the flow simultaneously with the pressure and/or temperature measurement. Existing studies have investigated the use of polystyrene microbeads for simultaneous flow barometry and velocimetry yet the polystyrene microbeads have a slow response time to changing pressures, making them incapable of resolving accurate pressures in fast flow applications such as wind tunnels. In this contribution, silicon dioxide and oxide-based multi-dye microbeads were characterized and found to have much faster response times than polystyrene-based microbeads. The pressure response times and sensitivity of these microbeads were tested to determine the most viable candidate for future unsteady applications. It will also be shown that the intensity-based approach applied to these microbeads coated on a glass slide can be used to accurately measure pressure with a significantly high measure of precision and low pressure uncertainties down to 106Pa. Finally, this paper will demonstrate the feasibility of using aerosolized pressure-sensitive microbeads for simultaneous barometry and velocimetry for fluid dynamic applications.