Experiment ID
| Balloon tests (hemispherical shape)
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Short Description
| A series of tests has been performed with nearly stoichiometric H2/air mixtures, enclosed in different sized hemispherical balloons with volumina of between 7.5 m3 and 2094 m3 (corresponding radii 1.5 m and 10 m), lying on the ground and being ignited by means of exploding wire or pyrotechnic ignitor with ignition energies of between 10 J and 1000 J. Flame speeds and pressure/time histories has been measured.
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What phenomena were studied
| At the beginning of gas explosion research the question arised, if there is a flame acceleration within initially quiescent, premixed and unconfined fuel/air mixtures because of instabilities in flame propagation (so-called flame induced turbulence) and if so, which would be the limit of the flame speed and corresponding overpressure for very large clouds.
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What phenomena / effects can be studied
| For stoichiometric hydrogen-air-mixtures for example, the flame speed limit is 125 m/s, corresponding to a peak overpressure of 130 mbars.
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Instrumentation
| Measurements included up to 12 piezoresistive pressure transducers, and up to 4 high speed cameras (side view and top view).
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Test variables
| Balloon radius: 1.5 m to 10 m
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Data description / Data completeness
| All pressure-time histories as hard copies; 16mm films; flame distance-time-diagrams as hardcopies
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Data availability
| Publicly accessible
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Source of data / Reference
| Fh-ICT-report (Dec. 1983): Ballonversuche zur Untersuchung der Deflagration von Wasserstoff/Luft-Gemischen
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Why were chosen
| Basic investigation on relation: cloud size/ flame speed
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Relevance to the project purposes
| Phenomena in very large clouds
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Experimental data
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Results of simulations
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