Numerical investigation of oxygen bubble condensation in subcooled quiescent liquid oxygen based on height function method

Abstract

Bubble condensation is a fundamental issue in the direct contact condensation (DCC) process, which is extremely hard to predict due to the intense mass transfer and flow instability. Aiming at the cryogenic oxygen bubble evolution and pressure oscillation, a modified energy balance mass transfer model is adopted based on the height function method. The height function method is used to calculate the real-time interfacial curvature, modifying the mass transfer rate that emerged in CFD simulation. The modified model is validated to be convincing and accurate by a steam bubble condensation simulation. The results indicate that the cryogenic bubbles condense faster with a more intense mass transfer process, compared with the near-room-temperature mediums. The corresponding amplitude of pressure oscillation for the cryogenic mediums is approximately 3 ∼ 4 times as larger as that for near-room-temperature mediums. It is found that both the condensation rate and the frequency of pressure oscillation are repressed with the increase of bubble volume. That means that a big bubble condensation might produce a low-frequency pressure oscillation. In addition, both the condensation rate and the intensity of the pressure oscillation increase with the increase of subcooling. The average amplitude of pressure oscillation has a power function law with subcooling. These conclusions provide a theoretical basis for a deep understanding of the cryogenic DCC process.