Optimization of the Deflagration to Detonation Transition : Reduction of length and time of transition
| Autor: | R. Sorin, D. Desbordes, R. Zitoun |
|---|---|
| Přispěvatelé: | Bonneau, Eliane, Laboratoire de combustion et de détonique (LCD), Université de Poitiers-ENSMA-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2006 |
| Předmět: |
Deflagration to detonation transition
Standard enthalpy of reaction Materials science [PHYS.HEXP] Physics [physics]/High Energy Physics - Experiment [hep-ex] Turbulence [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex] Mechanical Engineering Detonation General Physics and Astronomy Thermodynamics Activation energy [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex] law.invention law Speed of sound [PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex] Isobaric process Shchelkin spiral |
| Zdroj: | Combustion Explosion and Shock Waves Combustion Explosion and Shock Waves, 2006, 15 (2), pp.137-145 |
| Popis: | The aim of this experimental investigation is the study of Deflagration to Detonation Transition (DDT) in tubes in order to (i) reduce both run-up distance and time of transition (L DDT and t DDT) in connection with Pulsed Detonation Engine applications and to (ii) attempt to scale L DDT with λCJ (the detonation cellular structure width). In DDT, the production of turbulence during the long flame run-up can lead to L DDT values of several meters. To shorten L DDT, an experimental set-up is designed to quickly induce highly turbulent initial flow. It consists of a double chamber terminated with a perforated plate of high Blockage Ratio (BR) positioned at the beginning of a 26 mm inner diameter tube containing a “Shchelkin spiral” of BR ≈ 0.5. The study involves stoichiometric reactive mixtures of H2, CH4, C3H8, and C2H4 with oxygen and diluted with N2 in order to obtain the same cell width λCJ≈10 mm at standard conditions. The results show that a shock-flame system propagating with nearly the isobaric speed of sound of combustion products, called the choking regime, is rapidly obtained. This experimental set-up allows a L DDT below 40 cm for the mixtures used and a ratio L DDT/λCJ ranging from 23 to 37. The transition distance seems to depend on the reduced activation energy (E a/RT c) and on the normalized heat of reaction (Q/a 0 2). The higher these quantities are, the shorter the ratio L DDT/λCJ is. |
| Databáze: | OpenAIRE |
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