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Mécanisme d’accélération d’une flamme de prémélange hydrogène/air et effets sur les structures

Abstract : Flame acceleration and explosion of hydrogen/air mixtures remain key issues for severe accident management in nuclear power plants. Empirical criteria were developed in the early 2000s by Dorofeev and colleagues providing effective tools to discern possible FA or DDT scenarios. The objectives of the present work are to better understand the mechanisms of acceleration for premixed H2/air flames and to provide a solid base of experimental data for the validation of the codes used for safety analyses. The experiments were performed in an obstacles-laden tube (blockage ratio between 0.3 and 0.6) with 120 mm internal diameter and about 5 m length. The effects of the initial pressure and the nitrogen dilution on lean H2 mixtures have been studied. The results show that pressure promote flame acceleration only for highly reactive mixtures. Moreover, the overpressure induced by the combustion is directly proportional to the initial pressure. Besides, flame-shock interactions and thermo-diffusive instabilities play an important role in flame acceleration. A new technique to track the flame position along the tube has been developed in order to obtain a finer representation of the flame velocity profile. The method consists in performing time-resolved IR absorption measurements by doping the mixture with an alkane. The velocity profile is then derivedby measuring the variation of the extension in depth of the unburnt gas along the tube axis. Finally, analyses on the effects of combustion generated loads on stainless steel structures were performed in order to provide preliminary results for the design of a new experimental device.
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Submitted on : Wednesday, October 31, 2018 - 10:13:06 AM
Last modification on : Friday, December 7, 2018 - 3:09:36 AM
Long-term archiving on: : Friday, February 1, 2019 - 12:52:49 PM


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  • HAL Id : tel-01909397, version 1



Roberta Scarpa. Mécanisme d’accélération d’une flamme de prémélange hydrogène/air et effets sur les structures. Autre. Université d'Orléans, 2017. Français. ⟨NNT : 2017ORLE2046⟩. ⟨tel-01909397⟩



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