Behavior of the Cryogenic Propellant Tanks during the First Flight of the Ariane 5 ESC-A Upper Stage

Abstract

On February 12th 2005 the first flight of the new Ariane 5 cryogenic upper stage was successfully carried out. In the frame of a post-mission analysis the flight data has been evaluated in detail in order to investigate the propellant and thermodynamic behavior during the flight. Goal of the analysis is thus to understand the behavior of the propellant in the tanks and to study the accuracy of the applied numerical tools. During the flight assessment the whole mission, starting on the launch pad until passivation of the stage, has been examined. The document highlights certain mission phases such as the ballistic phase (separation of the payload) and the passivation phase. The passivation phase consists of a tank pressure reduction in order to avoid an uncontrolled later explosion. Various sensors inside the propellant tanks allow a correlation of the propellant location in the tanks with the performed numerical CFD predictions. The numerical analyses were carried out with the FLOW-3D software to simulate propellant sloshing and an in-house software for the thermodynamic behavior. The analyses demonstrate the capability of the numerical analyses to better understand the propellant behavior in the tanks, which is an advantage for future upper stage developments.