By John S. Allen, In Mei Sou, Christopher N. Layman, College of Engineering, University of Hawaii-Manoa Honolulu
For a variety of engineering applications, the simultaneous real-time measurements of the velocities and temperature changes in a flow field are needed. This is particularly important in the design and optimization of ultrasound systems used for mixing and sonochemistry. In this case, the ultrasound vibrations of an acoustic horn induce localized heating and streaming in the fluid inside a reactor. We present novel experimental results of the synchronized measurements of streaming velocities using a PIV (Particle Imaging Velocimetry) system (TSI, Shoreview, MN) with thermal measurements of the surface temperatures using a FLIR Titanium Thermal Camera (FLIR, Wilsonville, OR). The convective heat transfer is quantified with respect to the development of vortices in the flow field. Spatial correlation analysis is conducted between the temperature and fluid velocity fields. The combined effects of heating and streaming are examined for a range of fluids with different rates of thermal dissipation.