Expulsion of Entrapped Air in a Rapidly Filling Horizontal Pipe
Bibliographic record
Abstract
Air expulsion from an end-of-pipe orifice in a rapidly filling horizontal pipe is investigated experimentally and analytically in order to more completely characterize the system’s transient response. In particular, images of air–water patterns, air-volume variations, orifice flow regimes, and measured pressure histories are synchronized to elucidate the process of air expulsion. Air expulsion typically undergoes an early stage involving pressurization, expansion, and release of a portion of the initial air, events that generally occur even before the advancing water column reaches the pipe end. The next stage depends strongly on the orifice size. For a small discharge orifice, an oscillation of the residual air occurs with the discharge orifice being intermittently choked by water; by contrast, larger discharge orifices rapidly and completely expelled the air, often leading to high water-hammer pressures. Three distinct patterns of pressure oscillation are typically observed. With small orifices, the cushioning effect of the initial air tends to dominate, whereas slightly larger orifices lead to a more complex process of expulsion and more persistent and larger pressure oscillations. Even larger orifices often lead to severe water-hammer pressures. Thus, smaller orifices tend to result in smaller pressure fluctuations. As expected, both the initial-air volume and the inlet pressure significantly influence the transient response. A derived analytical model accurately captures the measured pressure oscillations during the intermittent release of residual air, including the water hammer that can arise due to suddenly arresting the liquid water column.
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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 | 0.001 |
| 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".