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Experimental observation of fast deflagrations and transition to detonations in hydrogen-air-mixtures
The present paper reports on experimentally obtained results of fast propagating deflagrations, the transition-process from deflagration to detonation, and detonations in hydrogen-air mixtures. These combustion phenomena are investigated by means of various sophisticated optical and conventional measurement-techniques like the Laser-induced Predissociation Fluorescence, which, in particular, gives a new insight into the understanding of these supersonic combustion-modes. Focus is put on the regime of the lean detonation-limit, depending on both, the mixture-composition and the dimension of the test-facility. For this limit criteria of empirical character have been applied for hydrogen-safety considerations until now. This study reports that a transition into a detonation of a fast-propagating flame is possible for leaner mixture-compositions as they are covered in the empirical criterion down to the theoretical detonation limit of the test-facility. It was observed that a detonation is not the most dangerous combustion mode. For mixture-compositions between the theoretical and the empirical detonation limit, it is as well possible that the flame propagates as a supersonic deflagration with the same velocity as the leading shock-wave. The peak-pressure of this combustion mode can be more than two-times higher compared to that of a detonation.
Experimental observation of fast deflagrations and transition to detonations in hydrogen-air-mixtures
The present paper reports on experimentally obtained results of fast propagating deflagrations, the transition-process from deflagration to detonation, and detonations in hydrogen-air mixtures. These combustion phenomena are investigated by means of various sophisticated optical and conventional measurement-techniques like the Laser-induced Predissociation Fluorescence, which, in particular, gives a new insight into the understanding of these supersonic combustion-modes. Focus is put on the regime of the lean detonation-limit, depending on both, the mixture-composition and the dimension of the test-facility. For this limit criteria of empirical character have been applied for hydrogen-safety considerations until now. This study reports that a transition into a detonation of a fast-propagating flame is possible for leaner mixture-compositions as they are covered in the empirical criterion down to the theoretical detonation limit of the test-facility. It was observed that a detonation is not the most dangerous combustion mode. For mixture-compositions between the theoretical and the empirical detonation limit, it is as well possible that the flame propagates as a supersonic deflagration with the same velocity as the leading shock-wave. The peak-pressure of this combustion mode can be more than two-times higher compared to that of a detonation.
Experimental observation of fast deflagrations and transition to detonations in hydrogen-air-mixtures
Eder, A. (author) / Gerlach, C. (author) / Mayinger, F. (author)
2000
9 Seiten, 9 Bilder, 2 Tabellen, 17 Quellen
Conference paper
English
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