different test scenarios of the LH2 propellant management device for a re-ignitable cryogenic upper stage during the ballistic flight phase (CFM LH2 PMD)

scheme of the PMD during the draining scenario

research area: fluid dynamics

experiment title:

Different Test Scenarios of the LH2 Propellant Management Device for a Re-ignitable Cryogenic Upper Stage during the Ballistic Flight Phase

experiment acronym: CFM LH2 PMD

funding agency: DLR

grant number: 50RL0921

performing organization:

ZARM, Universität Bremen

prime investigator: Prof. Dr. Michael Dreyer

experiment objective


One of the main tasks in the field of astronautics is the gas- and vapour-free propellant supply of the engines. One mission scenario is to reignite the cryogenic upper stage of the rocket during the ballistic flight phase. For re-ignition during the ballistic flight phase so-called Propellant Management Devices (PMDs) are required. PMDs are refillable reservoirs which are located near the tank outlet. The PMD shall provide an adequate amount of liquid, especially during the ballistic, unpowered flight phase, until they get refilled, e.g. by capillary structures inside the tank.

To observe the behaviour of fluids within the LH2 PMD different tests were performed under compensated gravity to simulate the ballistic flight phase. During the draining test a test liquid was drained out of the PMD through the feed lines. Critical aspects of this test were the flow rate and the conditions when gas is sucked inside the PMD (which further flows to the feed lines). During the gas ingestion test the behaviour of gas bubbles were examined. Under certain circumstances gas can occur in the feed lines. These gas bubbles must be removed from the feed lines. Here, the critical aspects were the amount and the flow rate of the gas which was put in the LH2 PMD.

experimental setup

test capsule for the draining scenario
prepared PMD model

experiment campaigns

experiment year: 2011
number of drops: 10
number of catapult flights: 1