Research On The Gas-liquid Two-phase Fluid Flow In Porous Channel

The pebble-bed water-cooled nuclear reactor, of which the core consists of spherical elements, is a new conception nuclear reactor. The power density of the pebble bed reactor is very much higher than other nuclear reactors. In order to study the hydraulics of pebble-bed water-cooled nuclear reactor, flow resistance characteristics of air-water two-phase flowing through circular tube packed with same glass balls were studied numerically.A full porous media filled channel model was developed by using of FLUENT 6.3. The appropriate solution model and boundary conditions were selected, and the appropriate parameters were set. The air-water two-phase flow was numerically simulated by solving the three dimensional N-S equation of the model. The air-water two phase flow through porous medium was preliminary simulated. From the cloud chart of the water and air, it was showed that the flow had entrance effect and export effect when it was through the porous media. The velocity distribution was not uniform at entrance, and near exit, the flow of fluid was unstable. Meanwhile, the characteristics and velocity of water flow and air flow were very similar. Through the comparison with the experimental results, it was showed that the model can well predict the air-water two-phase pressure drop in porous media tube under many conditions, of which the errors for dimension of 5mm and 8mm were 19.12% and 32%, and the total error was 26.28%. However, the errors of void fraction were large, and they were 61.37% and 42.59%, and the total error was 53.32%. Meanwhile, through the comparison with the volume fraction, it was showed that the result is very close to the homogeneous model. In the end, this paper tried to analyse this phenomenon form the drag force model of FLUENT.