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Journal Articles

Simulation of the self-propagating hydrogen-air premixed flame in a closed-vessel by an open-source CFD code

Thwe, T. A.; Terada, Atsuhiko; Hino, Ryutaro; Nagaishi, Ryuji; Kadowaki, Satoshi

Journal of Nuclear Science and Technology, 59(5), p.573 - 579, 2022/05

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The simulations of the combustion of self-propagating hydrogen-air premixed flame are performed by an open-source CFD code. The flame propagation behavior, flame radius, temperature and pressure are analyzed by varying the initial laminar flame speed and grid size. When the initial laminar speed increases, the thermal expansion effects become strong which leads the increase of flame radius along with the increase of flame surface area, flame temperature and pressure. A new laminar flame speed model derived previously from the results of experiment is also introduced to the code and the obtained flame radii are compared with those from the experiments. The formation of cellular flame fronts is captured by simulation and the cell separation on the flame surface vividly appears when the gird resolution becomes sufficiently higher. The propagation behavior of cellular flame front and the flame radius obtained from the simulations have the reasonable agreement with the previous experiments.

Oral presentation

Simulation of the behavior of spherically expanding H$$_{2}$$-air premixed flame

Thwe, T. A.; Hino, Ryutaro; Terada, Atsuhiko; Kadowaki, Satoshi

no journal, , 

We performed the two- and three-dimensional simulations to investigate the behavior of spherically expanding H$$_{2}$$-air premixed flame by using XiFoam. The equivalence ratio was set to unity. The ignition started from the center of domain, and the flame expanded spherically and became wrinkle. The obtained flame radius has the agreement with the experimental result.

Oral presentation

Approach to analysis of hydrogen combustion inside of radioactive waste vessels using CFD softwares based on an open source "OpenFOAM"

Thwe, T. A.; Terada, Atsuhiko; Hino, Ryutaro

no journal, , 

Since hydrogen is continuously generated and releases inside of high-level radioactive waste vessels, the awareness must be taken on the risk of hydrogen combustion and explosion. In hydrogen safety management, besides the experimental investigations, CFD approaches in predictions of flame propagation phenomena are of important role. As an approach to analysis of hydrogen combustion inside of vessels, we used the open source software, OpenFOAM and performed the simulations for propagation of H$$_{2}$$-air premixed flame. A new laminar flame speed model deduced from H$$_{2}$$-air explosion experiments by T. Katsumi et al. [Nagaoka Univ. Tech.] was implemented in the XiFoam solver and reproduced the propagation of H$$_{2}$$-air flame. Flame radius obtained by simulation agreed with the experimental results within 0.005s. Wrinkle flame formation was observed when the flame propagated outwardly as in experiments.

Oral presentation

Effects of mesh size on wrinkle behavior of H$$_{2}$$-air premixed flame inside of a vessel; Numerical simulations by using XiFoam

Thwe, T. A.; Terada, Atsuhiko; Hino, Ryutaro; Kadowaki, Satoshi

no journal, , 

For the risk reduction on hydrogen combustion and explosion due to hydrogen generated by radiolysis of water inside of high-level radioactive waste vessels, understanding the phenomena and characteristics of hydrogen combustion is necessary, and CFD approaches are of important role. In this numerical simulation, XiFoam solver was modified by adding a new laminar flame speed model deduced from experiment by Katsumi et al. (Nagaoka University of Technology). It reproduced the propagation of H$$_{2}$$-air premixed flame and we clarified the effects of mesh size (2 mm to 0.625 mm) on wrinkle behavior. The results showed that the mesh size should be equal to or less than 1.0mm to observe the wrinkle behavior of flame in which the flame temperature and radius for each mesh size were almost same at 0.003s to 0.006s, and then the former increased and the later became large due to intrinsic instabilities. The wrinkle flame shape from the simulation was similar to that from the experiment when the mesh size became small.

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