3D Effects of detonation re-initiation after diffraction at a back-facing step
Bibliographic record
Abstract
Detonation diffraction at a backward facing step and subsequent re-initiation at the bottom wall at near critical detonation transmission conditions is studied in a square 7.6 cm channel. The experimental techniques used for this purpose include ultra high-speed schlieren video from the side and the top views. Direct photography is also performed in the top view configuration with a soot foil placed at the bottom wall after the step. The process of detonation re-initiation is studied for 2H2+O2+2Ar and CH4+2O2 mixtures that are characterized by a very regular and irregular detonation cellular structure, respectively. For both mixtures detonation re-initiation begins at discrete points where the descending transverse reflect from the bottom wall; the spacing of re-initiation points matches the wave number, suggesting the three-dimensional interaction of descending and lateral transverse waves on the reflecting wall trigger detonation re-initiation. The subsequent growth of these re-initiation kernels differs between mixtures. For regular cell mixtures, the detonation evolution is gradual and follows the lateral transverse wave along the bottom wall; whereas for irregular cell mixtures, explosive of hot spots grow independently of the lateral transverse waves. The observed initiation processes underscore the critical role of three-dimensional effects for both regular and irregular cell mixtures. The abrupt detonation initiation observed for methane-oxygen can be attributed to the high effective activation energy, i.e., high reaction rate temperature sensitivity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".