A Propellant Management Device (PMD) is used to ensure vapor-free supply of propellant for the engine. For the new Ariane V upper stage two types of PMD's are analized. Here the one for the LH2 tank is described.
The proposed LH2-PMD is attached at the lower LH2-tank hemisphere. The reservoir is positioned to the propellant port of a tear drop tank, frequently used in spin-stabilized satellites with apogee boost motor. Hence, propellant can easily be expelled while the tank rotates. No additional settling acceleration is necessitated. The reservoir will always be partially filled even at low tank fill levels.
Inside of the LH2-PMD housing several baffle plates are included. Four vertical baffles suppress liquid motion and stabilize the liquid flow during ballistic flight phases. The plates support the gas expulsion into the main propellant tank. Additionally, they function as vanes for the liquid propellant.
In case of the refilling process under microgravity the location of the PMD at the outside of the tank is favorable. Acceleration and capillary forces drive trapped gas bubbles out of the reservoir. Due to angular velocities as well as resulting acceleration during chill-down bubbles move from the screen area towards the top holes of the PMD into the LH2 tank.
The functionality of this PMD will be demonstrated by different test scenarios: the experiments performed under terrestrial conditions will demonstrate the capability of the PMD during the driven flight phases. On the other hand, the experiments performed in a the drop tower will represent the function of the PMD during ballistic flight phases.