Experimental and numerical analysis of sloshing in annular sectored containers under tangential direction excitation

In many third-generation pressurized water reactor (PWR) nuclear power plants, large annular passive cooling water tanks are typically installed atop the containment structure to assist in dissipating residual heat from the reactor during station blackout and other accident conditions. These tanks are partitioned by radial walls into multiple sectored compartments. Due to their elevated position, these annular sectored tanks exhibit strong seismic responses. In particular, under long-period ground motions, liquid sloshing inside the tanks can impose additional hydrodynamic loads on the structure, potentially compromising its structural integrity. Therefore, a thorough investigation into the sloshing behavior of such tanks under seismic excitation is essential for ensuring their seismic safety. At present, experimental studies on annular sectored tanks under large-amplitude sloshing conditions are very limited. Moreover, the applicability and accuracy of existing numerical methods in handling such complex scenarios require further validation and assessment. To address this, the present study conducts both experimental and numerical investigations of annular sectored tanks. A scaled shaking table test is performed to systematically analyze the modal characteristics and transient response of sloshing under tangential excitation. The effects of excitation intensity, tank geometry, and excitation direction on key parameters such as wave height and hydrodynamic pressure are evaluated. In terms of numerical simulation, three approaches are employed: a finite element-based acoustic-structure coupling method, a CFD-based Volume of Fluid (VOF) method, and a two-way fluid-structure interaction (FSI) method. The simulation results are compared with experimental data to verify the accuracy and applicability of each approach under various conditions. The findings of this study provide valuable insights for seismic response assessment and structural optimization of annular sectored passive cooling tanks.