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Balloon Tests

Experiment ID Balloon tests (hemispherical shape)
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.
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.
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.
Instrumentation Measurements included up to 12 piezoresistive pressure transducers, and up to 4 high speed cameras (side view and top view).
Test variables Balloon radius: 1.5 m to 10 m
Data description / Data completeness All pressure-time histories as hard copies; 16mm films; flame distance-time-diagrams as hardcopies
Data availability Publicly accessible
Source of data / Reference Fh-ICT-report (Dec. 1983): Ballonversuche zur Untersuchung der Deflagration von Wasserstoff/Luft-Gemischen
Why were chosen Basic investigation on relation: cloud size/ flame speed
Relevance to the project purposes Phenomena in very large clouds
Experimental data
Results of simulations
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Page last modified on October 14, 2009, at 11:43 AM