As lessons learnt from the Fukushima Daiichi nuclear power plant accident, reviews of the safety of nuclear facilities have been conducted in the world. One of the important objectives of counter measures of nuclear reactor system is suppressing diffusion of radioactive materials. To suppress diffusion of radioactive materials to environment at severe accident of a nuclear reactor system, instalment of filtered venting devices and releasing high pressure pollutant gas to the atmosphere with elimination of radioactive materials from the gas are one of most useful counter measures.

 

There are a lot of filters to remove micro particles from gas. As one of these filters, so called water filter is used as air pollution control equipment, and water filter is used as one of the filters for filtered venting devices.

 

In the water filter, two-phase flow is formed by using gas and water, and micro particles in gas are captured in water through the gas-liquid interfaces formed between gas and water. To improve performance of the water filter and to consider the most effective operation, capturing mechanism and detail behavior of flow inside the water filter must be understood. However, two-phase flow in the water filter is very complicated and it is difficult to understand the detail behavior of two-phase flow, especially the gas-liquid interface. Then, numerical simulation is one of the important tools to understand phenomena and to evaluate performance of the water filter.

 

Then, the numerical simulation method to understand phenomena and to evaluate performance of the water filter for filtered venting devices is developed in Japan Atomic Energy Agency (JAEA). This simulation method is based on two-phase flow simulation code TPFIT developed in JAEA. To simulate the capturing the behavior of micro particles through interface, not only micro particle motion, but also the shape and velocity of interface and velocity distribution of two-phase flow must be evaluated. TPFIT is numerical simulation code for two-phase flow, and can simulate interface behavior, such as deformation, movement and the breakup of the interface, and velocity distribution of each phase. In addition, to simulate micro particles in two-phase flow, so called the Lagrangian particle tracking (LPT) method was incorporated to TPFIT.

 

In this paper, outline of developing simulation method is explained. As a driving force of micro particles, in addition to an inertia force, a drag force and a gravity force, we newly introduce the Brownian force to our simulation method. Moreover, the effects of these forces on micro particle motion in the two-phase bubbly flow will be discussed.


Numerical Simulation of Microparticles Motion in Two-Phase Bubbly Flow

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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