Fluid distribution in a two-phase space accumulator predicted by a coupled multi-scale model based on single-domain approach

Two-phase accumulator is a key component of thermal control systems in space. For fluid management in microgravity, internal structures such as capillary vanes and porous meshes are fabricated inside the vacant flow region in the accumulator. This generates a problem of transient two-phase flow in multi-scale structures with the coexistence of free flow region and porous media. For precise thermal control, the structural design of the complex internal structures is critical for the space accumulator. The motivation of this work is to examine the two-phase flow dynamics in a novel space accumulator and provide adequate information for optimization of the internal structures. Thus, we build a coupled multi-scale numerical model to simulate the two-phase flows in the cross-scale structures inside the accumulator. The model is based on the single-domain approach: the Brinkman momentum equation is applied to porous media region with a volume-averaging method upscaling pore-scale flow properties to macroscopic scale. The Level Set method is incorporated into the model to capture the interface of the two phases. The model is validated by several fundamental experimental cases. The dynamics of fluid distribution inside the accumulator are demonstrated, and the influences of the key parameters are studied systematically.