Numerical investigation on the mechanism of geyser in cryogenic fluid pipes

摘要

In order to study the mechanism of geyser in cryogenic fuel system, a CFD model based on VOF method for two-phase heat and mass transfer process is established and validated. The detailed transient behavior and the whole formation process of geyser in a cryogenic pipe are successfully captured and predicted. The prediction performance of 3-D, 2-D axisymmetric and 2-D planar model is evaluated. The formation and development of the whole geyser process are clearly revealed by visualization and macroscopic parameter analysis, and a contrastive study is performed to investigate the mechanism of the pressure peak in a geyser. It is found that: The incubation stage occupies the largest portion of geyser period up to 95% in the presented condition and there is a dramatic pressure fall in the eruption stage and a pressure spike in the refilling stage, which leads to a periodic shock of pressure. The violent depressurization boiling is the main cause of the eruption. Moreover, the water hammer induced by vapor condensation will bring about a huge pressure increase, and it becomes the main mechanism for the pressure spike in the refilling stage.