Recent DDT simulations and criteria based on experimental and numerical results for hydrogen safety studies Part 2: HGF-H2 project
Recent DDT simulations and criteria based on experimental and numerical results for hydrogen safety studies Part 2: HGF-H2 project
In this report, we will first briefly describe the phenomena, underlying mechanisms andnecessary criteria of DDT, then summarize the experimental work on hydrogenexplosion performed at the SWL of RWTH Aachen. Then we will explain the CFDcodes SHOCKIN and AIXCO as well as the applications in the simu...
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Personal Name(s): | Wang, Boliang |
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Rehm, Werner | |
Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
2001
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Physical Description: |
III, 59 p. |
Document Type: |
Report Book |
Research Program: |
ohne Topic |
Series Title: |
Berichte des Forschungszentrums Jülich
3930 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
In this report, we will first briefly describe the phenomena, underlying mechanisms andnecessary criteria of DDT, then summarize the experimental work on hydrogenexplosion performed at the SWL of RWTH Aachen. Then we will explain the CFDcodes SHOCKIN and AIXCO as well as the applications in the simulation of DDTprocesses.Studies performed at the SWL include three topics: 1) self-ignition phenomena;2) DDT mechanisms in axis-symmery geometry with periodic obstacles or a singleobstacle; and 3) detonation formation at the entrance to narrow gaps. A database ofignition delay times and schlieren records has been set up for hydrogen-air-steam/COZmixtures. Excellent photographs concerning shock reflections and ignition wereproduced providing good materials for the validation of computer codes.Based on the preparatory work at the SWL, a new two-dimensional CFD code(SHOCKIN), which describes the feedback of the flow fields with chemical reactions,has been successfully developed. This code takes into account all species andelementary reactions defined by the user, or uses a two-step kinetic model for the globalreaction processes. First test cases for validation of the calculations were carried out forexperimental results with schlieren pictures. The results show that the code works quitewell. It was then used to simulate hydrogen events in a reactor containment. With theassumptions applied, it is concluded from the simulation results that the most probableignition position is at the axis of symmetry in those test cases studied. The test casesdemonstrated that it will be possible to define DDT conditions in large-scale geometriesinitiated by shock wave reflection and focusing effects.Improvements to the AIXCO code, developed at the Institute of Mechanics ofthe RWTH Aachen for the numerical simulation of three-dimensional compressiblereactive flows, have been made in three respects at ISR1: 1) enabling a temperaturegradient in the computation domain as an initial condition for the SWACERmechanism, 2) enabling a shock front at any position in the computation domain as aninitial condition, and 3) introduction of a temperature switch concept which takes the"hot spots" effect into account. With the improved AIXCO, spontaneous DDT inducedby temperature gradients (SWACER mechanism), DDT by shock reflections and DDTby a "hot spot" ahead of a flame front were achieved. |