Computation of Air Discharge into a Water Pool by Using Volume-of-Fluid Method

摘要

This study is contributed to volume-of-fluid modeling of air discharge into a water pool that occurs in early stage of suppression tank operations. Existing experiment is simulated with the STAR-CCM+ version 10.04. Blowdown pipe flow, local temperature and pressure variations are discussed in comparison with the measurements. Cyclic bubble growth and detachment at the blowdown pipe exit inside the water pool and resulting flow rate oscillations are well simulated. For the local temperatures, the analyses overestimate the measurements and this is due to underprediction of interfacial transports in the homogeneous volume-of-fluid model. However, computed pressure variations are relatively in good agreement with the measured data. Turbulence effect is also investigated and it is found that the temperature oscillation is larger for the laminar case due to lower viscosity than for the turbulence case. However, the average oscillation frequencies for the laminar and turbulence cases are not so different from each other. In the future, simulations of air and/or steam discharge are planned considering more sophisticated models for two-phase interfacial transport.