Development of Fiber-Optic Probes to Measure Two-Phase Flow Dynamic Parameters in Support of Flow-Induced Vibration Studies
Bibliographic record
Abstract
Flow-induced vibration in two-phase flows requires the knowledge of flow regime and detailed flow characteristics. This paper outlines the development of fiber-optic probes to measure void fraction, local flow velocity and characteristic size (i.e., bubble diameter) of the two-phase mixture. The principle of operation of such probes is based on the difference in index of refraction between the liquid phase and the gas phase when in contact with a fiber-optic probe supplied with a laser light. The reflected signal levels for the gas phase and the liquid phase are very different thus providing a reliable measure of void fraction. The paper describes the development of fiber-optic probes for measurements of internal two-phase flow in pipes and of external flow across a tube bundle. The use of double probes allows the measurements of local flow velocity and bubble size. Some detail measurements of flow in the gap between tubes in cross flow are presented. The fabrication of the very small and fragile probes required much development effort. The paper describes the difficulties and the solutions to assure good quality probes. Some data processing and data interpretation issues are also discussed.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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".