Detonation attenuation and quenching in hydrogen mixtures after the interaction with cylinders
Bibliographic record
Abstract
The attenuation and quenching of H$_2$/O$_2$ detonations transmitted across a column of cylinders were studied experimentally and analytically at sub-atmospheric pressures. Two distinct transmission regimes were observed: successful transmission and complete quenching. The transition between the two regimes was found to correlate with the ratio of inter-cylinder separation distance (b) to a characteristic detonation scale for large blockage ratios (BRs), with critical limits comparable with those previously reported for detonation diffraction from slots. Based on available cell size measurements, the critical transmission limit was $b/λ=4.5\pm3$. The proposed theoretical model based on Whitham's geometric shock dynamics confirmed the equivalence between the detonation diffraction at abrupt area changes and around cylinders with large BRs. Complete quenching observed experimentally was accounted for by the weak transmitted shock strength upon detonation failure. For the tested BRs, the transmitted shock speed ranged between 50% and 60% of the Chapman-Jouguet detonation speed. As a result, the post-shock temperatures fell below the cross-over regime for hydrogen ignition, leading to very long ignition delay times ($t_i$) despite the temperature rise induced by Mach reflection. The long $t_i$ suppressed auto-ignition, while the high isentropic exponent prevented further convective mixing required for re-initiation. This explained the fundamental difference between arresting hydrogen and hydrocarbon detonations, for which transmitted fast flames punctuated by auto-ignition events were always observed. The transmitted shock strength was found to be well-predicted by our previous self-similar multiple discontinuity gas-dynamic model. Over a very narrow range near the critical conditions, both hot spot re-ignition and detonation re-initiation from Mach shock reflections were observed.
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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 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| 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".