Surface oscillations within a fuel tank during acceleration can be amplified when acceleration is reduced at main engine cut off. Such sloshing is undesirable as it can disturb the space vehicle, but it can be controlled by positioning baffles in the tank.
In an experimental test at Nasa’s Marshall Space Flight Center, located in Huntsville, Alabama, CFD tools were used to evaluate the propellant sloshing in the fuel tank.
In the experimental test, sloshing in a scale fuel tank was recorded with high speed photography during a 4.3s free fall from rest. The sudden dropping of the tank is equivalent to the reduction in acceleration experienced by the launch vehicle.
For the simulations, the geometry was created using CFX in about 3hr. With a mesh of 26, 624 cells, the run time was 8.8 CPU minutes on a Silicon Graphics R400. The standard surface tension and multiphase models within CFX were used, and agreement with experimental results was excellent.