Speaker
Description
This talk presents an overview of recent and ongoing activities at the von Karman Institute dedicated to the experimental analysis of flow configurations relevant to space propellant management. Specifically, the talk will present the results from Sloshing PARabolic flight Experiment (SPARGE) campaigns, the last Contact Angle Sloshing Experiment (CASE) campaign and describe the NT-SPARGE (Non-isoThermal) experiment currently in preparation. All these campaigns took (or will take) place during ESA Parabolic Flight Campaigns organized in collaboration with NOVESPACE.
The SPARGE experiments are dedicated to the experimental characterization of isothermal liquid sloshing in partially filled reservoirs subjected to a microgravity environment. This is a configuration of fundamental importance to launchers and satellites alike because liquid sloshing can potentially hamper the supply of engine feedlines and challenge Guidance, Navigation and Control (GNC) systems to cope with unexpected accelerations. The SPARGE campaign provided a comprehensive characterization, including high-speed visualization, interface tracking and Particle Image Velocimetry (PIV) of water and HFE7200 during the transition from hypergravity (~1.8g) to microgravity. The different properties of the two liquids play a role in the dynamic response of the system, showing different reaction time during the step to microgravity.
The CASE experiment was dedicated to the dynamics of capillary tubes in microgravity, with a focus on the impact of interface re-orientation and dynamics contact angles. Capillary driven flows in microgravity are essential in capillary fluidic systems that include gas-liquid separators, urine collection and processing, condensing heat exchangers and liquid sorbent CO2 scrubbers, to mention but a few. The CASE experiment reproduced the capillary driven flow in tubes of varying diameters, thus promoting various levels of velocity and acceleration, and exploring a broad range of operating conditions. High-speed visualization and PIV have been used to calibrate dynamic models for capillary flows for each of these.
The NT-SPARGE campaign in preparation will target the experimental analysis of the thermohydraulic of a partially filled reservoir undergoing thermal disturbances and sloshing. This project extends the previous SPARGE campaigns in isothermal conditions to a non-isothermal condition with phase change. With sufficient long holding time, a partially filled reservoir tends to reach slightly subcooled conditions in the liquid and slightly superheated conditions in the ullage gas. Heat leakages or refilling operations can further exacerbate this thermal gap and promote thermal stratification in the liquid. In these conditions, the sudden enhancement of heat and mass transfer coefficients, due to a sloshing event, can result in sudden condensation or evaporation phenomena which, in turn, produce significant (and undesired) pressure fluctuations. NT-SPARGE aims at characterizing the thermal response of a partially filled reservoir during sloshing in microgravity and use the available data to calibrate simplified models for the tank thermodynamics.
| Keywords | sloshing, propellant management, capillary systems |
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