A concept of volume porosity together with model of moving walls were elaborated and implemented into the COM3D code. Additionally to that a support of real-time data exchange with finite-element code ABAQUS - © Dassault Systèmes provided possibility to perform simulations of the gas-dynamic simultaneously with geometrical adaptation of environmental conditions. Based on the data obtained in the KIT combustion experiments in narrow gaps [1], the authors performed a series of the simulation on the combustion in the corresponding conditions. Obtained numerical results demonstrated good agreement with the observed experimental data. These data were also compared with those obtained in the simulation without wall bending, where simulation showed considerably different combustion regime. Application of the developed technique allows to obtain results unreachable without accounting on wall displacements, which demonstrates massive over-estimation of the pressures observed during flame propagation.

This paper describes a methodology for simulating the structural response of vented enclosures during hydrogen deflagrations. The approach adopted entails full spatial mapping of explosion loads predicted with the computational fluid dynamics (CFD) tool FLACS-Hydrogen to the non-linear finite element (FE) IMPETUS Afea solver. The modelling involves one-way coupling of pressure loads taken from either experiments or CFD simulations to the FE solver. The performance of the combined model system is evaluated for vented hydrogen deflagrations in 20-foot ISO containers. The work is part of work package 3 (WP3) in the project ‘Improving hydrogen safety for energy applications through prenormative research on vented deflagrations’ (HySEA).

The paper presents the outcomes of the HyResponse project i.e. the European Hydrogen Safety Training Programme for first responders. The threefold training is described: the content of the educational training is presented, the operational training platform and its mock-up real scale transport and hydrogen stationary installations are detailed, and the innovative virtual tools and training exercises are highlighted. The paper underlines the outcomes the three pilot sessions as well as the Emergency Response Guide available on the HyResponse’s public website. The next steps for widespread dissemination into the community are discussed.

The aim of this study is to assess the probability of the damage to hydrogen fueling station personnel exposed to the hydrogen explosion shock wave. A three-dimensional mathematical model of the explosion of hydrogen-air cloud formed after the destruction of the high-pressure storage cylinders is developed. A computer technology how to define the personnel damage probability field on the basis of probit analysis of the generated shock wave is developed. To automate the process of computing the "probit function-damage probability" tabular dependence is replaced by a piecewise cubic spline. The results of calculations of overpressure fields, impulse loading, and the probability of damage to fueling station personnel exposed to the shock wave are obtained. The mathematical model takes into account the complex terrain and three-dimensional non-stationary nature of the shock wave propagation process. The model allows to obtain time-spatial distribution of damaging factors (overpressure in the shock wave front and the compression phase impulse) required to determine the three-dimensional non-stationary damage probability fields based on probit analysis. The developed computer technology allows to carry out an automated analysis of the safety situation at the fueling station and to conduct a comparative analysis of the effectiveness of different types of protective facilities

This paper shows the numerical investigation on the self-ignition behavior of high pressure hydrogen released from the tube. The present study aims to clarify the effect of parameters on the behavior and duration of self-ignition outside the tube using two-dimensional axisymmetric numerical simulation with detailed chemistry. The parameters in this study are release pressure, tube diameter and tube length. The strength of the spherical shock wave to keep chemical reaction and expansion are important factors for self ignited hydrogen jet to be sustained outside the tube. The trend of strength of spherical shock wave is enhanced by higher release pressure and larger tube diameter. The chemical reaction weakens due to expansion and the degree of expansion becomes larger as the spherical shock wave propagates. The characteristic time for the chemical reaction becomes shorter in higher release pressure, larger tube diameter and longer tube diameter cases from the induction time under constant volume assumption. The self ignited hydrogen jet released from the tube is sustained up to the distance where the characteristic time for chemical reaction is shorter than the characteristic time for the flow to expand, and higher release pressure, larger tube diameter and longer tube length expand the distance where the tip flame can propagate downstream. For the seed flame which is the key for jet fire, the larger amount of the ignited volume when the shock wave reaches the tube exit contributes to the formation and stability of the seed flame. The amount of the ignited volume tends to be larger in the longer tube length, higher release pressure and larger tube diameter cases.

Experiments were performed on the influence of oxidants (air, pure oxygen O2 and pure nitrous oxide N2O at atmospheric pressure) in the straight expansion tube after the burst disk on the hydrogen spontaneous ignition. The lowest pressure at which the spontaneous ignition is observed has been researched for a 4 mm diameter tube with a length of 10 cm for the two oxidant gases. The ignition phenomenon is observed with a high speed camera and the external overpressures are measured. Numerical simulations have also been conducted with the high resolution CFD approach detailed chemistry formerly developed by Wen and co-workers. Comparison is made between the predictions and the experimental data.

Successful transition to a hydrogen economy calls for a deep understanding of the risks associated with its widespread use. Accidental ignition of hydrogen by hot surfaces is one of such risks. In the present study, we investigated the effect that rotation has on the reported ignition thresholds by numerically determining the minimum surface temperature required to ignite stoichiometric hydrogen-air using a hot horizontal cylinder rotating at various angular velocities, ω. Numerical experiments showed a weak but interesting dependence of the ignition thresholds on rotation: the ignition thresholds increased by 8 K, from 931 K to 939 K, with increasing angular velocity (0 ≤ ω ≤ 240 rad/s). A further increase to ω = 480 rad/s resulted in a decrease in ignition surface temperature to 935 K. Detailed analysis of the flow patterns inside the vessel and in close proximity to the hot surface brought about by the combined effect of buoyancy and rotation, as well as of the distribution of the wall heat flux along the circumference of the cylinder, support our previous findings in which regions where temperature gradients are small were found to be prone to ignition

A better understanding of chemical kinetics under volumetric expansion is important for a number of situations relevant to industrial safety including detonation diffraction and direct initiation, reflected shock-ignition at obstacles, ignition behind a decaying shock, among others. The ignition of stoichiometric hydrogen-air mixtures was studied using 0D numerical simulations with time-dependent specific volume variations. The competition between chemical energy release and expansion-induced cooling was characterized for different cooling rates and mathematical forms describing the shock decay rate. The critical conditions for reaction quenching were systematically determined, and the thermo-chemistry dynamics were analyzed near the critical conditions.

Power to gas could get an important issue in future, permitting the valorisation of green electric excess energy by producing hydrogen, mixing it with natural gas (NG) and use the NG grid as temporary storage. NG grid stakeholders expect that blends up to 20% seem to be a realistic scenario. The knowledge of the explosion group for these hydrogen/NG (H2NG) mixtures is a necessary information for the choice of equipment and protective systems intended for the use in potentially explosive atmospheres of these mixtures. Therefore, we determined experimentally the minimum ignition current (MIC), the MIC ratios referenced on MIC of pure methane, corresponding to IEC 60079-20-1 standard. The results are compared to those obtained by maximum experimental safe gap (MESG), the second standardized method. The tested gas mixtures started from 2 vol.% volume admixture in methane rising in 2% steps up to 20 vol.% of hydrogen. The interpretation of these results could conduct to consider methane/hydrogen mixtures containing more than 14 vol.% of hydrogen as Group IIB gases.

A series of experiments in a thin layer geometry performed at the HYKA test site of the KIT. The experiments on different combustion regimes for lean and stoichiometric H2/air mixtures were performed in a rectangular chamber with dimensions of 20 x 90 x h cm3 , where h is the thickness of the layer (h = 1, 2, 4, 6, 8, 10 mm). Three different layer geometries: (1) a smooth channel without obstructions; (2) the channel with a metal grid filled 25% of length and (3) a metal grid filled 100% of length. Detail measurement of H2/air combustion behavior including flame acceleration (FA) and DDT in closed rectangular channel have been done. Five categories of flame propagation regimes were classified. Special attention was paid to the analysis of critical condition for different regimes of flame propagation as function of the layer thickness and roughness of the channel. It was found that thinner layer suppresses the detonation onset and even with a roughness, the flame is available to accelerate to speed of sound. The detonation may occur only in a channel thicker than 6 mm.