Influences of a small obstacle on the sidewall upon a detonation cellular structure
We experimentally investigated the influences of a small obstacle on the sidewall upon a detonation cellular structure using the smoked-foil technique for a stoichiometric hydrogen–oxygen mixture diluted with argon at pressures ranging from 15 to 60 kPa. The obstacles were of four types: forward-fac...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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The Japan Society of Mechanical Engineers
2023-05-01
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| Series: | Journal of Thermal Science and Technology |
| Subjects: | |
| Online Access: | https://www.jstage.jst.go.jp/article/jtst/18/1/18_23-00038/_pdf/-char/en |
| _version_ | 1797785490424856576 |
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| author | Yoko SEKI Wookyung KIM Tomoyuki JOHZAKI Takuma ENDO |
| author_facet | Yoko SEKI Wookyung KIM Tomoyuki JOHZAKI Takuma ENDO |
| author_sort | Yoko SEKI |
| collection | DOAJ |
| description | We experimentally investigated the influences of a small obstacle on the sidewall upon a detonation cellular structure using the smoked-foil technique for a stoichiometric hydrogen–oxygen mixture diluted with argon at pressures ranging from 15 to 60 kPa. The obstacles were of four types: forward-facing steps and slopes and backward-facing steps and slopes. The step height was varied and set to 1, 2, or 5 mm, but the slope height was fixed at 5 mm. The forward-facing slope angle was set to 40° or 75°, and the backward-facing slope angle was set to 20° or 40°. Under all conditions, for the forward-facing steps and slopes, the detonation cellular structure was negligibly affected, except for the region around the tip of the step and slope. However, for the backward-facing step, the detonation re-activation phenomenon occurred downstream of the obstacle. In addition, the enlarged cellular pattern due to the rarefaction wave and the trajectory of the re-activated strong transverse wave were observed downstream of the obstacle. Furthermore, a finer cellular pattern was observed downstream of the re-activation phenomenon. The distance between the backward-facing step and the re-activation position zra was fitted well by a power-law relation of the step height |h| and the cell width of the steadily propagating detonation λCJ as zra/λCJ = 2.7(|h|/λCJ)0.80. When the obstacle was the backward-facing slope, the smoked-foil records could be classified into two types based on whether the signatures of the detonation re-activation phenomena were clearly observed or not. Finally, when the finer cellular pattern was observed, the behavior of the cell-width enlargement subsequent to the re-activation phenomenon was similar in all cases, and the characteristic length required for the finer cellular pattern to relax to the steady-state pattern was approximately 10 times zra. |
| first_indexed | 2024-03-13T00:55:47Z |
| format | Article |
| id | doaj.art-10b0fe3641824b19a7753cad2a8e0779 |
| institution | Directory Open Access Journal |
| issn | 1880-5566 |
| language | English |
| last_indexed | 2024-03-13T00:55:47Z |
| publishDate | 2023-05-01 |
| publisher | The Japan Society of Mechanical Engineers |
| record_format | Article |
| series | Journal of Thermal Science and Technology |
| spelling | doaj.art-10b0fe3641824b19a7753cad2a8e07792023-07-07T00:15:52ZengThe Japan Society of Mechanical EngineersJournal of Thermal Science and Technology1880-55662023-05-0118123-0003823-0003810.1299/jtst.23-00038jtstInfluences of a small obstacle on the sidewall upon a detonation cellular structureYoko SEKI0Wookyung KIM1Tomoyuki JOHZAKI2Takuma ENDO3Mechanical Engineering Program, Hiroshima UniversityMechanical Engineering Program, Hiroshima UniversityMechanical Engineering Program, Hiroshima UniversityMechanical Engineering Program, Hiroshima UniversityWe experimentally investigated the influences of a small obstacle on the sidewall upon a detonation cellular structure using the smoked-foil technique for a stoichiometric hydrogen–oxygen mixture diluted with argon at pressures ranging from 15 to 60 kPa. The obstacles were of four types: forward-facing steps and slopes and backward-facing steps and slopes. The step height was varied and set to 1, 2, or 5 mm, but the slope height was fixed at 5 mm. The forward-facing slope angle was set to 40° or 75°, and the backward-facing slope angle was set to 20° or 40°. Under all conditions, for the forward-facing steps and slopes, the detonation cellular structure was negligibly affected, except for the region around the tip of the step and slope. However, for the backward-facing step, the detonation re-activation phenomenon occurred downstream of the obstacle. In addition, the enlarged cellular pattern due to the rarefaction wave and the trajectory of the re-activated strong transverse wave were observed downstream of the obstacle. Furthermore, a finer cellular pattern was observed downstream of the re-activation phenomenon. The distance between the backward-facing step and the re-activation position zra was fitted well by a power-law relation of the step height |h| and the cell width of the steadily propagating detonation λCJ as zra/λCJ = 2.7(|h|/λCJ)0.80. When the obstacle was the backward-facing slope, the smoked-foil records could be classified into two types based on whether the signatures of the detonation re-activation phenomena were clearly observed or not. Finally, when the finer cellular pattern was observed, the behavior of the cell-width enlargement subsequent to the re-activation phenomenon was similar in all cases, and the characteristic length required for the finer cellular pattern to relax to the steady-state pattern was approximately 10 times zra.https://www.jstage.jst.go.jp/article/jtst/18/1/18_23-00038/_pdf/-char/endetonationre-activationsmall obstaclesidewallsmoked foil |
| spellingShingle | Yoko SEKI Wookyung KIM Tomoyuki JOHZAKI Takuma ENDO Influences of a small obstacle on the sidewall upon a detonation cellular structure Journal of Thermal Science and Technology detonation re-activation small obstacle sidewall smoked foil |
| title | Influences of a small obstacle on the sidewall upon a detonation cellular structure |
| title_full | Influences of a small obstacle on the sidewall upon a detonation cellular structure |
| title_fullStr | Influences of a small obstacle on the sidewall upon a detonation cellular structure |
| title_full_unstemmed | Influences of a small obstacle on the sidewall upon a detonation cellular structure |
| title_short | Influences of a small obstacle on the sidewall upon a detonation cellular structure |
| title_sort | influences of a small obstacle on the sidewall upon a detonation cellular structure |
| topic | detonation re-activation small obstacle sidewall smoked foil |
| url | https://www.jstage.jst.go.jp/article/jtst/18/1/18_23-00038/_pdf/-char/en |
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