Characterizing the influence of upstream obstacles on very low head water-turbine performance
Bibliographic record
Abstract
The effect of an upstream obstacle – a backward-facing step (BFS) – on a very low head (VLH) water-turbine model has been investigated. The motivation of this study was to quantify the interaction between the VLH turbine and BFS, an abstraction of typical obstacles present in existing channels. Power measurements were obtained for three configurations; the turbine in the absence of the BFS was first examined as a baseline test, followed by configurations with the BFS placed at distances of half a turbine diameter and one turbine diameter upstream. It was found that turbine efficiency is comparable between the case with no step upstream and when the step is placed at one diameter. However, the configuration at half a diameter exhibited an efficiency deficit of approximately 7%. Particle image velocimetry measurements were then used to quantity the flowfield associated with loss in efficiency from the no step to the half a diameter step configuration. It was determined that the losses could be attributed to a highly non-uniform inlet velocity profile, which results in unsteady loading across the turbine blades.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".