Abstract
In this manuscript, neutron radiography (NR) flow measurement techiques, which can measure the void fraction of boiling flow in narrow metal channels, were described. These techniques, high-frame-rate NR (NFR-NR) and NR3DCT, have been developed to study the void fraction and critical heat flux models. Measurement systems are consist of water-circulating loop with a NR test section, pre-heater, separator, condenser and DC power supply to generate the vapor, neutron-visible light converter, camera system which is automatically controlled by the computer and CT system in case of NR3DCT. NR images are processed on teh parallel super computer system. Exclusive image processing and visualizatio software calculates the void fraction and crops the data. Instantaneous void fraction can be measured by HFR-NR with time-resolution of 1ms. Spatial void fraction distribution can be measure by NR3DCT with spatial-resolution of 100μm. These two NR techniques make up the loss mutually, and we can obtain the spatial void fraction with high time resolution.
