Results of the HySafe CFD Validation Benchmark SBEPV5

The different CFD tools used by the NoE HySafe partners are applied to a series of integral complex Standard Benchmark Exercise Problems (SBEPs). All benchmarks cover complementarily physical phenomena, addressing application relevant scenarios, and refer to associated experiments with an explicit usage of hydrogen. After the blind benchmark SBEPV1 and SBEPV3 with subsonic vertical release in a large vessel and in a garage like facility, SBEPV4 with a horizontal under-expanded jet release through a small nozzle, SBEPV5 covers the scenario of a subsonic horizontal jet release in a multi-compartment room.
As the associated dispersion experiments conducted by GEXCON, Norsk Hydro and STATOIL were disclosed to the participants the whole benchmark was conducted openly. For the purpose of validation, only the low momentum test D27 had to be simulated.
The experimental rig consists of a 1.20 m x 0.20 m x 0.90 m (Z, vertical) vessel, divided into 12 compartments, partially even physically by four baffle plates. In each compartment a hydrogen concentration sensor is mounted. There is one vent opening at the wall opposite the release location centrally located about 1 cm above floor with dimensions 0.10 m (Y) times 0.20 m (Z). The first upper baffle plate close to the release point is on a sensitive location as it lies nearly perfectly in the centre of the buoyant jet and thus separates the flow into the two compartments. The actual release was a nominally constant flow of 1.15 norm liters for 60 seconds. With a 12mm nozzle diameter this corresponds to an average exit velocity of 10.17 m/s.
6 CFD packages have been applied by 7 HySafe partners to simulate this experiment: ADREAHF by NCSRD, FLACS by GexCon and DNV, KFX by DNV, FLUENT by UPM and UU, CFX by HSE/HSL, and GASFLOW by FZK. The results of the different participants are compared against the experimental data. Sensitivity studies were conducted by FZK using GASFLOW and by DNV applying KFX.
Conclusions based on the comparisons and the sensitivity studies related to the performance of the applied turbulence models and discretisation schemes in the release and diffusion phase are proposed. These are compared to the findings of the previous benchmark exercises.