Two-phase Fluid Solid Coupling Modeling: Theory, Numerical Model, and Application

Abstract

Underground compressed air energy storage (CAES) is seen as an important and promising way for balancing electrical power system. Many large-scale CAES projects (≥300 MW) are being planned in China, some of which have already been permitted for construction. Despite the benefits from CAES, some challenges arise in area of construction technology, operation system, maintenance and monitoring methods. One of the challenges lies in the evaluation of air leakage effect on flow and stress field around the underground cavern. Therefore, considering the actual physical field characteristics, the mathematical formula of mass conservation equations for air and water in porous media, as well as equilibrium equations for solid mechanics are established first and then coupled together for numerical solutions. The constitutive models for solid and porous fluid adopt classical elastic and Darcy’s law respectively, while the air-water interaction adopts classical van-Genuchten model and contributes to solid mechanics by pore pressure. Numerical implementations are based on secondary development to COMSOL software. Then interpretations to simulation results and the comparison with results not taking damage effect into account are made.