Non-Intrusive Visualization of Optically Inaccessible Flow Fields Utilizing Positron Emission Tomography

Abstract

A technology gap persists in the visualization of optically inaccessible flow fields such as those in integrated systems. Advances in positron emission tomography (PET) technology are enabling its use in the engineering field to address this technology gap. This paper discusses a numerical study performed to characterize a modern PET system’s ability to reconstruct a three-dimensional mapping of the optically inaccessible flow field downstream of an orifice. A method was devised to simulate a ring detector response to a flourine-18 radioisotope/water solution injected into the flow through a standard thickness pipe with orifice. A commercial computational fluid dynamics code and the GEANT4 Applications for the Tomographic Emission Monte Carlo simulation physics package were used to carry out the simulations. Results indicate that geometrical features, such as the pipe internal diameter, can be resolved to within a few millimeters with specific activity levels of 155 Bq/Voxel (91.2 Bq/mm3), and acquisition times as low as 15 s. Results also suggest that flow features, such as the radial extent of the shear layer between the primary and secondary recirculating flow can be resolved to within 5 mm with the same activity level, but with acquisition times of 45 s.