Analytical model for a leak detection system on Ariane 5 launcher cryogenic interfaces.

Ariane 5 ECA launcher includes two cryogenic stages with both liquid hydrogen and liquid oxygen propellants. Tightness check of launcher interface valves is performed before lift-off. For the liquid hydrogen isolation valve of first stage, this check is made by measuring the pressure rise of the on-board / ground interface control volume which was previously flushed and purged of liquid propellant. This paper presents an analytical thermo-hydraulic model of the ground line supplying liquid hydrogen to first stage of Ariane 5 ECA launcher, with the purpose to study the sensibility of various parameters influencing the pressure evolution in the on-board / ground interface control volume during tightness check.