Fluid Dynamic Aspects of the Porous Wetted Wall Protection Scheme for Inertial Fusion Energy Reactors

A numerical and experimental investigation has been conducted to analyze the fluid dynamic aspects of the porous wetted wall protection scheme for inertial fusion energy (IFE) reactor first walls. A level contour reconstruction method has been used to track the three-dimensional evolution of the liquid film surface on porous downward-facing walls with different initial film thickness, liquid injection velocity through the porous wall, surface disturbance amplitude, configuration and mode number, liquid properties, and surface inclination angle. Generalized charts for the computed droplet detachment time, detached droplet equivalent diameter, and minimum film thickness during the transient for various design parameters and coolant properties are presented.

In order to validate the numerical results over a wide range of parameters, an experimental test facility has been designed and constructed to simulate the hydrodynamics of downward-facing porous wetted walls. Nondimensionalization of the model shows that water can be adequately used as a simulant to validate the numerical results. Preliminary experimental results show good agreement with model predictions. The results of this investigation should allow designers of conceptual IFE reactors to identify appropriate "windows" for successful operation of the porous wetted wall protection concept for different coolants.