Effect of a baffle on slosh waves excited by gravity-gradient acceleration in microgravity

2003

J. Fluid Mech.

This paper presents a comprehensive analysis of the transport processes that control the self-pressurization of a cryogenic storage tank in normal gravity. A lumped thermodynamic model of the vapour region is coupled with the Navier-Stokes and energy equations governing heat, mass and momentum transport in the liquid. These equations are discretized using a Galerkin finite-element method with implicit time integration. Three case studies are considered based on three different heating configurations imposed on the tank wall: liquid heating, vapour heating and uniform heating. For each case, the pressure and temperature rise in the vapour and the flow and temperature distributions in the liquid are determined. Results are compared to a lumped thermodynamic model of the entire tank. It is shown that the final rate of pressure rise is about the same in each case and close to that predicted by thermodynamics even though the actual pressures are different because of varying degrees of thermal stratification. Finally, a subcooled liquid jet is used to mix the liquid and limit the pressure rise. Even so, there is still some thermal stratification in the liquid, and as a result the final vapour pressure depends on the particular heat distribution.

Section: Introductionmentioning

confidence: 99%

On the validity of purely thermodynamic descriptions of two-phase cryogenic fluid storage

Panzarella

2003

J. Fluid Mech.

“…These experiments could be classified into two categories: those where phase change was present and those where it was absent. In the latter category, investigations were typically concerned with slosh dynamics, 8,9 or mixing characteristics/flow profiles in the liquid. [10][11][12] The other category of experiments studied self-pressurization 13 and different pressure control strategies.…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study of Tank Pressure Control in Reduced Gravity

Barsi

44th AIAA Aerospace Sciences Meeting and Exhibit

2006

Recent studies suggest that Zero Boil-Off (ZBO) technologies, aimed at controlling the pressure inside cryogenic storage tanks, will play a prominant role in meeting NASA's future exploration goals. Small-scale experiments combined with validated and verified computational models can be used to optimize and then to scale up any future ZBO design. Since shortcomings in previous experiments make validating comprehensive two-phase flow models difficult at best; the Zero Boil-Off Tank (ZBOT) experiment has been proposed to fly aboard the International Space Station. In this paper, a numerical model has been developed to examine several test points in the ZBOT test matrix. Specifically, a numerical model is developed to evaluate four pressure control strategies after the tank undergoes a period of self-pressurization. The four strategies include axial liquid jet mixing, mixing provided by a sub-cooled liquid jet, bulk liquid cooling provided by a cold-finger and coldfinger cooling with axial jet mixing. Results indicate, that over the time scales under consideration, sub-cooled liquid jet mixing is the most effective means to reduce tank pressure.

“…17 Investigations in this category have focused on: evolution of the free surface as influenced by the microgravity environment, 18 reorientation of the vapor subject to spacecraft thrust, 19 free surface deformation as affected by the jet flow and geysers 17,20 or by external forces, such as magnetic fields 21,22 and fluid slosh coupled to gravity-gradient accelerations or spacecraft dynamics. 23,24 The studies in this category are all limited to isothermal models, and, again, divulge no information with respect to tank pressurization.…”

Section: Introductionmentioning

confidence: 99%

Ventless Pressure Control of Two‐Phase Propellant Tanks in Microgravity

Annals of the New York Academy of Sciences

Panzarella

2004

This work studies pressurization and pressure control of a large liquid hydrogen storage tank. A finite element model is developed that couples a lumped thermodynamic formulation for the vapor region with a complete solution of the Navier-Stokes and energy equations for the flow and temperature fields in the liquid. Numerical results show that buoyancy effects are strong, even in microgravity, and can reposition a vapor bubble that is initially at the center of the tank to a region near the tank wall in a relatively short time. Long-term tank pressurization with the vapor bubble at the tank wall shows that after an initial transient lasting about a week, the final rate of pressure increase agrees with a purely thermodynamic analysis of the entire tank. However, the final pressure levels are quite different from thermodynamic predictions. Numerical results also show that there is significant thermal stratification in the liquid due to the effects of natural convection. A subcooled jet is used to provide simultaneous cooling and mixing in order to bring the tank pressure back down to its initial value. Three different jet speeds are examined. Although the lowest jet speed is ineffective at controlling the pressure because of insufficient penetration into the liquid region, the highest jet speed is shown to be quite effective at disrupting thermal stratification and reducing the tank pressure in reasonable time.