Numerical investigation on flow condensation process during interphase mixing in oxygen pipeline of liquid rocket

AbstractThis paper presents a numerical study on the flow condensation of high temperature gas oxygen in subcooled flowing liquid oxygen and the corresponding mixing process in the oxygen pipeline of a liquid rocket propulsion system. A computational fluid dynamics model is established with the interfacial phase change solved by user‐defined function, and flow field details such as phase distribution and flow condensation length required for safety operation of liquid rocket engine are obtained. Experimental validation of numerical model is performed with HCFC123 as the working fluid, and the calculated void fraction and flow condensation length of gas show good agreement with those of experimental data. The numerical result indicates that when the gas oxygen is injected into the pipeline, continuous annular gas film forms in the vertical section and then accumulates in the inner side of the bend section due to the centrifugal force. Rapid condensation of oxygen occurs in the following horizontal section due to the enhanced interphase heat transfer by the transverse relative motion. The condensation length of gas oxygen varies with the inlet gas/liquid flow rate ratio, liquid subcooling, and inlet velocity. The operable gas/liquid ratio ranges for complete gas condensation in the given bend pipe is obtained for various liquid inlet parameters.