Sloshing and pressurization tests for membrane tank: Tests, validation and models

This paper presents recent 1:1 scaled tests results for sloshing, pressurization and evacuation behaviour in membrane tanks used for spacecrafts and satellites. The first 1:1 scale sloshing test setup evaluates fluid reaction forces for axial, lateral and spin excitations at different fill level. Evaluation and determination of sloshing forces during relevant flight phases is important for flight stability and GNC layout. The test evaluates the impact of pressure level, membrane position, acceleration level and excitation direction. Mathematical reaction force models for accelerated and ballistic flight phases are presented. The second 1:1 scale pressurization test setup shows the transient membrane position during Helium pressurization and evacuation at realistic flow rates. During launch in depressurized condition the mechanical impact on the membrane launch may be reduced in the membrane tank such that the membrane is supported by the tank wall and surrounded by vapour and dissolved gas below the membrane. The tests provide important information of the membrane state for drying, filling procedures and on-flight pressurizations effects. The membrane position during depressurization is dependent on fill level, vapour generation, dissolved gas amount in the test fluid and pressurization rate. The paper evaluates this evaporation and condensation effect below the membrane during the depressurization and repressurization process. Video recordings show the membrane position and gas state inside the membrane tank. In addition complementary test in a vacuum chamber are presented to support the analysis and allow optical observation from the outside