Scientists of Lithuanian Energy Institute have recently collaborated with colleagues from other European TSOs and ETSON partners in research activities – BARCO and ETSON-SAMHYCO-NET benchmarks.

ETSON-SAMHYCO-NET benchmark is a collaborative undertaking with the aim of enabling model enhancement and validation of turbulence and steam effect on hydrogen flame propagation since it is not well reproduced by combustion models usually implemented in safety assessment tools. The benchmark consisted of simulating experiments, performed in the ENACCEF2 facility. 13 organisations from 8 countries participated in the benchmark, organized within four steps with blind and open phases, providing 10 computational fluid dynamics (CFD) contributions and 3 contributions based on lumped-parameter (LP) approach.

LEI scientists participated in the benchmark by providing both LP and CFD results. LP simulations were performed with ASTEC code developed by IRSN, thus contributing to the code validation and gaining the experience required for safety applications. CFD simulations were performed with an open-source turbulent combustion solver flameFoam, developed by LEI scientists using OpenFOAM toolkit.

Since flameFoam is a comparatively new solver still in the development phase and requires model refinement and validation, ETSON-SAMHYCO-NET benchmark was a valuable opportunity for LEI developers to evaluate solver capabilities regarding hydrogen flame simulation under severe accident relevant conditions – the effects of turbulence, steam, and initial temperature and pressure.

Code to code analysis and comparisons with experiments showed that flameFoam mostly corresponds to the state-of-the-art currently achieved in the field and demonstrated by benchmark partners. However, present modelling shortcomings and needed improvements were also highlighted. Blind simulation results obtained with flameFoam showed a tendency to overestimate flame velocity at 1 bar initial pressure and to significantly underestimate the influence of higher initial pressure. Obtained validation status is of high value for the improvement of flameFoam combustion models and the experience obtained in ETSON-SAMHYCO-NET benchmark will be considerably beneficial for further solver development and refinement.