Numerical Simulation of High Pressure Hydrogen Releases into Air through Varying Orifice Geometries
Bibliographic record
Abstract
Computational Fluid Dynamics (CFD) is employed to investigate the near exit jet behavior of a high-pressure hydrogen release into the quiescent ambient air through different types of orifices. The effect of orifice geometry on the structure, development and dispersion of highly under-expanded hydrogen jet is numerically investigated. Various shapes of orifices are evaluated including holes with constant areas such as elliptical and circular openings, and deforming apertures under different configurations and conditions considering the interactions of enlarging of circular openings and the release time, as well as the deformation of a circular hole to an elliptical hole. A three-dimensional in-house parallel code is exploited to simulate the flow using an unstructured tetrahedral finite volume Euler solver. The transport (advection) equation is applied to track the shape and the location of the hydrogen - air interface. The Abel-Nobel real gas law is used since high-pressure hydrogen flow deviates from the ideal gas assumption. Comparative studies between the dispersion of hydrogen jet issuing from different types of orifices in terms of jet development and pressure expansion are carried out. The numerical simulations indicate that in addition to the hydrogen storage pressure, the shape and the size of the orifice influence the hydrogen jet development which can affect the ignition risks associated with the accidental release of hydrogen.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 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".