Cryogenic Tank Modeling for the Saturn AS-203 Experiment

Abstract

A computational fluid dynamics (CFD) model is developed for the Saturn S-IVB liquid hydrogen (LH2) tank to simulate the 1966 AS-203 flight experiment. This significant experiment is the only known, adequately-instrumented, low-gravity, cryogenic selfpressurization test that is well suited for CFD model validation. A 4000-cell, axisymmetric model predicts motion of the LH2 surface including boil-off and thermal stratification in the liquid and gas phases. The model is based on a modified version of the commerciallyavailable FLOW3D software. During the experiment, heat enters the LH2 tank through the tank forward dome, side wall, aft dome, and common bulkhead. In both model and test the liquid and gases thermally stratify in the low-gravity natural convection environment. LH2 boils at the free surface which in turn increases the pressure within the tank during the 5360 second experiment. The Saturn S-IVB tank model is shown to accurately simulate the self pressurization and thermal stratification in the 1966 AS-203 test. The average predicted pressurization rate is within 4% of the pressure rise rate suggested by test data. Ullage temperature results are also in good agreement with the test where the model predicts an ullage temperature rise rate within 6% of the measured data. The model is based on first principles only and includes no adjustments to bring the predictions closer to the test data. Although quantitative model validation is achieved €or one specific case, a significant step is taken towards demonstrating general use of CFD for low-gravity cryogenic fluid modeling. Nomenclature AX= smallest radial cell size, in PULL, END = end ullage pressure , psia Nx = numberofxcells t RUN = simulation run time, hrs NZ = number ofzcells TLQ ,END = end liquid temperature, R NTOT = total number of cells TULL ,END = end ullage temperature, R

Hydrogen in Space Applications

“…A multitude of validation tests performed with different similitude liquids will not be sufficient and some representative tests are mandatory to provide a final validation, that is, tests in a low gravity environment with liquid hydrogen must be performed. This demonstration flight was performed in 1966 [5] and remains today a reference for computational code validation and to understand various phenomena linked to liquid hydrogen behavior in a low gravity environment [11]. The first in-flight experiments in the early 1960s [10] used several sounding rockets with a spherical liquid hydrogen tank (Figure 40.6).…”

Self-Pressurization and Spray Cooling Simulations of the Multipurpose Hydrogen Test Bed (MHTB) Ground-Based Experiment

“…However, many of these models have only studied tank selfpressurization [5][6][7] . Several have investigated tank pressure control, but mainly for applications where an axial forced jet is used to perform thermal destratification through liquid mixing [8][9][10][11] .…”

Influence of phase change on self-pressurization in cryogenic tanks under microgravity

“…Roh and Son [10] neglected the vapor side transport contribution to the gas generation due to evaporation in a cryogenic liquid natural gas tank but no experimental comparisons were attempted. Grayson et al [11] included transport in the vapor and developed a model for the phase change effects at the liquid-gas interface in the so-called FLOW-3D code. Experimental validation for the CFD model was achieved for cryogenic tanks in low-gravity with a high heat leak and big vapor volume.…”