RANS-Based CFD Simulation of Jet-Induced Mixing and Jet Impingement on Large Bubble in Microgravity

Abstract

For National Aeronautics and Space Administration’s space mission planning, tons of cryogenic propellants need to be stored under microgravity conditions. Because of heat leaks into cryogenic propellant tanks, thermal stratification develops from lack of natural convection leading to boil-off of precious propellants. A thermodynamic vent system operates with a jet mixer to reduce thermal gradients within the fluid and control pressure inside the tank. In this work, a Reynolds-averaged Navier-Stokes–based computational fluid dynamics model was developed to study the fluid dynamics of jet-induced mixing and jet impingement on the large ullage bubble in the Tank Pressure Control Experiment (TPCE) under microgravity conditions. First, the computational model was benchmarked against existing experimental flow visualization data on the jet impingement. The jet mixing was then compared quantitatively with correlations for the jet radius to analyze the volumetric flow rate of the jet due to entrainment in the near field of the nozzle. The findings show that the confinement of the jet due to the ullage and the walls contributes positively to the jet entrainment rate, thus increasing the jet volumetric flow rate. In addition, the turbulence parameters are plotted to study the flow development for the TPCE case where the jet does not penetrate the ullage. Last, the model was used to determine the jet Weber number for penetration on the ullage bubble by varying jet inlet velocities. Numerical results show that the jet can penetrate the ullage when the jet Weber number is greater than 1.3.

Keywords:

• Jet mixing
• bubble impingement
• microgravity
• Tank Pressure Control Experiment
• computational fluid dynamics simulation

Acronyms

AHTR:	=	Advanced High Temperature Reactor
CFD:	=	computational fluid dynamics
CFM:	=	cryogenic fluid management
CSF:	=	continuum surface force
LAD:	=	liquid acquisition device
LOCA:	=	loss-of-coolant accident
NASA:	=	National Aeronautics and Space Administration
RANS:	=	Reynolds-averaged Navier-Stokes
SFR:	=	sodium fast reactor
SST:	=	shear stress transport
TKE:	=	turbulent kinetic energy
TPCE:	=	Tank Pressure Control Experiment
TVS:	=	thermodynamic vent system
VOF:	=	volume of fluid
1-D:	=	one-dimensional
2-D:	=	two-dimensional

Acknowledgments

The authors at Rensselaer Polytechnic Institute would like to thank the technical support provided by Michael F. Harris of NASA Kennedy Space Center. The authors would also like to thank the technical support from Mamoru Ishii of Purdue University and Wei Ji of Rensselaer Polytechnic Institute.

Disclosure Statement

No potential conflict of interest was reported by the authors.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by an Early-Stage Innovations grant from the NASA’s Space Technology Research Grants Program.