Oscillation Flow Induced by Underwater Supersonic Gas Jets from a Rectangular Laval Nozzle
Bibliographic record
Abstract
In present work, direct measurements of the interfacial behavior of water-submerged gas jets, with nozzle operated in over-expansion to highly under-expansion conditions, were performed using high-speed digital photography. The experimental results show that the two low-frequency oscillations, which are so called jet necking/bulging and necking/back-attack phenomenon, are also found in the region near present rectangular nozzle exit.As the nozzle pressure ratio increased, two distinct flow regimes can be observed: One that showed unstable gas/water interfacial characteristics for nozzle pressure ratio, NPR or Po/Pa≤ 10.17 when the jet pattern showed similar shape as the one issuing from axisymmetric nozzles, and the other with stable jet pattern for NPR > 18.48 when a 3D cross-like cross section jet gas/water boundary started to form and grow from the nozzle exit. Finally, numerical analysis on shockwave structures of the experimental nozzle models was carried out, and the submerged jet gas/water interface characteristics show good agreement with the jet boundaries predicted by numerical simulations. The numerical results indicate that the over-expanded flow in the four corner regions as well as the recompression shock wave may play a dominant role in the interface instability to result in necking/bulging and necking/back-attack phenomenon during over-expanded to slightly under-expanded conditions.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".