Modeling Interfacial Turbulent Heat Transfer during Ventless Pressurization of a Large Scale Cryogenic Storage Tank in Microgravity

Abstract

A two-phase CFD model for pressurization of cryogenic storage tanks is presented using both the Sharp Interface and VOF approaches for representing the phase boundary and the associated interfacial heat, mass and momentum transfer between the liquid and the vapor regions. Both models were validated against the microgravity pressurization data provided by the Saturn S-IVB AS-203 experiment, with the VOF model producing better agreement. Since proper representation of turbulence effects is crucial for predicting interfacial heat and mass transfer with fidelity, two different engineering models for turbulence, namely, the k- and the Shear-Stress Transport (SST) k- are considered. The fidelity of the two turbulence models for storage tank problems is assessed. The impacts of different turbulent parameters associated with the models, such as initial distributions of the respective turbulent quantities and different interfacial boundary conditions, are also studied. The results of our study underscore the fact that accurate modeling of turbulent interfacial heat transfer is crucial for predicting correct self-pressurization and thermal stratification in the cryogenic storage tank. In this context all the important aspects of turbulent modeling at the interface need to be properly addressed. This includes: 1) initial turbulence level; 2) interfacial turbulence B.C.; 3) the contribution of interface deformations to the enhancement of the interfacial turbulent heat transfer.