High-frame rate imaging of two-phase flow in a thin rectangular channel using fast neutrons

Area of Science:

• Nuclear Engineering
• Fluid Dynamics
• Imaging Science

Background:

• Two-phase flows are crucial in many industrial processes.
• Non-invasive imaging techniques are needed for studying these flows.
• Fast neutron radiography offers unique penetration capabilities.

Purpose of the Study:

• To demonstrate the feasibility of high-frame-rate fast neutron radiography for air-water two-phase flows.
• To analyze different flow regimes and measure key parameters.
• To assess the potential of this technique for future research.

Main Methods:

• Utilized a high-intensity fast neutron beam (average energy 6 MeV) generated from a Be target and 11.5 MeV deuterons.
• Employed a specialized fast-neutron imaging detector for high-frame-rate image acquisition (down to 10 ms exposure times).
• Conducted experiments on air-water two-phase flow in a thin rectangular channel.

Main Results:

• Achieved high-frame-rate neutron radiography of various two-phase flow regimes (bubbly, slug, churn).
• Successfully measured critical two-phase flow parameters, including volumetric gas fraction, bubble size, and mean bubble velocities.
• Demonstrated the feasibility of the technique for dynamic flow analysis.

Conclusions:

• Fast neutron radiography is a viable technique for high-speed, non-invasive imaging of two-phase flows.
• The developed method allows for quantitative analysis of flow dynamics.
• Future improvements can further enhance the resolution and application scope of this technique.