A flow visualization study on self-ignition of high pressure hydrogen gas released into a tube

Experimental and numerical study on spontaneous ignition of hydrogen and hydrogen-methane jets in air

“…A similar value of 2.5 MPa was provided by Golub et al [4] in their numerical investigations. The conclusion regarding the observed ignition spot position in the vicinity of the wall [12] is also consistent with the previously performed numerical research [17]. The conclusions regarding tube diameter influence did not determine clearly its impact on the ignition (see Fig.…”

“…The main conclusion regarding these works was that the ignition probability increases when there is an increase in the tube length [3e10]. The paper of Kim et al [12] was devoted to flow visualisation in the rectangular (10 Â 10 mm) channel utilizing a combination of shadowgraph, high-speed direct photography as well as pressure and lightness sensors. The initial ignitions were always observed in the boundary layer of the mixing zone and the flame spreads to the whole mixing zone.…”

Self-ignition of hydrogen–nitrogen mixtures during high-pressure release into air

“…Comparison with experimentally obtained results showed that the criterion for sustained jet fire is that all of reacting regions should merge into the one reacting zone before the gas leaves the tube. This conclusion is consistent with previously referenced works [13,20]. Another observable condition for ignition to take place is the sufficient number of transverse waves reflections in the tube, determined here as 3-4.…”

“…The comparison shows that the ignition with the following combustion may be sustained only if three ignition spots are present and merge into the one reaction zone before leaving the tube which was recorded during the experiments as the photodiodes showed clear signal at the time of driver gas left the extension tube. The ignition criterion of merged ignition zones near the wall and in the axis was previously reported by Lee et al [20] and 5.0 cm experimentally confirmed by Kim et al [13]. Another common feature of all of the simulated cases considered (see Fig.…”

“…In recent years one could observe an increased interest in hydrogen technologies and safety issues corresponding to them, including uncontrolled ignition during discharge into the air from high-pressure installations. Latest experimental [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] as well numerical [19][20][21][22][23][24] works focus mainly on the detailed description of the self-ignition mechanism according to different initial and boundary conditions including: extension channel geometry: diameter [4][5][6][7]19], length [5][6][7][8][9][10][11][12][13][14][15][16][17][20][21][22], cross-section shape [7,8,18,23] or obstacle presence in front of the hydrogen stream [18,…”