In the work package WP3.1 of the PRESLHY project the blow-down behavior of cryogenic hydrogen stored at elevated pressure is investigated by the project partners Karlsruhe Institute of Technology (KIT) and Pro-Science (PS). The main purpose of WP3.1 was to provide validation or reference data for • models defining or using a discharge coefficient, • subsequent explosion tests, where the released gases will be ignited (see E5.2), and • electrostatic field excitation and associated ignition potential of high-pressure hydrogen gas jets at cryogenic temperatures.

In part B of WP3.1 of the PRESLHY project 12 hydrogen blow-down experiments were performed with the Cryostat-facility on a free field-test site located a few kilometers to the north of KIT Campus North. About half of the experiments were made with liquid hydrogen at cryogenic temperatures (approx. 20 K). In the experimental campaign, the same release branch as in the related DisCha-experiments of Task 3.1A was used to facilitate comparison with the experiments of this series. For the same reason, five of the blow-down tests were made under ambient temperature conditions, since in part A also half of the matrix was performed under these conditions. The tests showed very good reproducibility. Besides the discharge characteristics and the transient jet behavior also the electrostatic fields have been recorded to understand potential mechanisms for spontaneous ignition.