Thermal Radiation Investigations of Real-Scale Hydrogen Jet Flames at High Pressure

In order to reduce global warming, the use of hydrogen as a renewable energy source is becoming more important. To enable this transition, unprecedently large amounts of hydrogen need to be safely transported and stored. Since hydrogen is usually stored and transported under pressure, one scenario to be considered is the release of hydrogen from a leakage with subsequent ignition. The resulting jet flame must be characterized with respect to the thermal radiation emitted into the environment to define safety distances. Various models that characterize the resulting flame shape and radiation already exist in the literature, but these are mainly based on empirical data from hydrocarbon jet flames. To verify the applicability of these models to hydrogen, real-scale tests are carried out at the BAM Test Site Technical Safety (BAM-TTS) with the aim to assess the flame geometry and the emitted thermal radiation. Parameters such as leakage diameter (currently 1 mm to 10 mm), pressure (currently up to max. 250 bar) and mass flow (up to max. 0.5 kg/s) are varied. In particular, the focus is laid on the measurement and modelling of the thermal radiation. The challenge here is the characterization of the flame geometry in an open environment and its impact on the thermal radiation. Existing heat radiation data from the literature are mostly based on unsteady outflow conditions. The experimental setup used here allows for the generation of a steady-state outflow for several minutes and thus a direct comparability with existing (steady-state) models.