Application of high frame-rate neutron radiography to liquid-metal two-phase flow research

3D Velocity Vector Measurements in a Liquid-metal using Unsharpness in Neutron Transmission Images

“…Thus, the image unsharpness includes the information of the distance between the object and the screen. As it is known, the measured profile can be expressed by the following convolution [4]:…”

“…In order to predict the flow behavior of a gas-molten metal mixture in a pool precisely, it is essential to examine the applicability of the existing model to the gas-molten metal mixture pool, and if necessary, to propose suitable constitutive relations in the momentum exchange between phases. From this point of view, present authors [2,3] performed study on the flow characteristics of nitrogen gasmolten lead bismuth eutectic (LBE) mixture in a rectangular pool and measured the void fraction distribution and time averaged liquid velocity field using neutron imaging and particle image velocimetry techniques [4].…”

Validation of X-ray radiography for characterization of gas bubbles in liquid metals

“…The measured value is in a very good agreement with the value calculated from the gas flow rate and bubble detachment frequency (d  6.42 mm). The significant deviations with respect to the bubble number and size can be attributed to the strong differences in the surface tension and the wetting behavior at the injection nozzle [14]. Bubbles undergo the maximum deformation just after the detachment from the nozzle.…”

“…However, the value of experiments carried out in real liquid metal flows depends on the availability of trustworthy and efficient measurement techniques. Previous measurements in liquid metal bubbly flows were performed by means of ultrasound Doppler velocimetry (UDV) [10], by conductivity probes [11], by Local Lorentz force velocimetry (LLFV) [12] or by neutron radiography [13,14]. Most of these techniques have limitations.…”

Velocity Measurement Techniques for Liquid Metal Flows

“…A very recent development is the application of high frame-rate neutron radiography to investigate liquid metal two-phase flows. Saito et al [65,66] performed experiments using the JRR-3M nuclear research reactor providing high neutron fluxes. Gold-cadmium particles were added to a lead-bismuth melt, and 2D velocity fields were reconstructed using particle tracking velocimetry.…”