Design of an anemometer to characterize the flow in the rotor rim ducts of a hydroelectric generator
Bibliographic record
Abstract
Due to its complex geometry, the airflow within hydroelectric generators is difficult to characterize. Although Computational Fluid Dynamics (CFD) can be a reliable engineering tool, its application to the field of hydroelectric generators is quite recent and has certain limitations, which are in part due to geometrical and flow complexities, including the coexistence of moving (rotor) and stationary (stator) components. For this reason, experimental measurements are required to validate CFD simulations of such complex flows. To this end, a 1:4 scale model of a hydroelectric generator was constructed at the Institut de recherche d’Hydro-Québec (Hydro Québec’s Research Institute - IREQ) and measurements using Particle Image Velocimetry (PIV) were performed to characterize the flow therein. However, this technique cannot be used in machines and thus, new flow sensors must be developed to measure the flow in the confined and harsh regions in these machines. The main region of interest is the flow within the rotor rim ducts, since it is directly responsible for cooling the poles (one of the most critical components). This rather complex task required the design of an anemometer that had to be accurate, durable, cost-effective, easy to install, and able to withstand the extreme conditions found in hydroelectric generators (temperatures of 45°C, centrifugal forces of 300 g, etc.). In this thesis, a thermal mass flow meter and a method for validating its performance, using hot-wire anemometry and a static model of a rotor rim, was developed. The sensor is equipped with two uniquely designed features: i) a heating element made of an array of Nichrome wires and ii) Resistance Temperature Detectors (RTDs) made of Balco wires. This design is capable of: i) measuring the mass flow rate in the rotor rim ducts with an accuracy of approximately 10%, ii) fitting inside small rectangular ducts (12.2 mm by 51 mm), iii) resisting forces up to 300 g, and iv) making measurements that are not altered by the magnetic fluxes found in the rotor poles.
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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) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".