Thermal Control of the Cryogenic Upper Stage of ARIANE 5 Midlife Evolution

摘要

In the frame of the ESA project ARIANE 5 Midlife Evolution a new cryogenic upper stage is currently under development. The new upper stage shall be used together with the existing main stage and boosters, extending the successful family of ARIANE 5 launchers. For the first time in a European launcher, the new cryogenic upper stage is capable of LEO and GTO missions including long ballistic phases and multiple boost phases, featuring a re-ignitable engine. The resulting wide domain of functional temperatures implies the necessity of a well-defined thermal control concept in order to meet the requirements of the individual parts and the performance even for mission durations of several hours. In particular, the long ballistic phases exact the development to new strategies regarding cryogenic propellant management and insulation concepts. Thermal design and ballistic phase strategy definition are challenging aspects regarding the complex thermodynamic processes in the cryogenic tanks, taking into consideration e.g. sub-cooling of liquid oxygen or the heat transfer in micro-gravity environment. The thermal concept is outlined in selected examples. The approach, using dedicated thermal analyses and tests as well as synergies from the existing cryogenic upper stage ESC-A, is described.