Effects of End Plates and Blockage on Low-Reynolds-Number Flows Over Airfoils
Bibliographic record
Abstract
Measurements on airfoils at low Reynolds numbers can have a strong dependence on the experimental setup as a result of the sensitivity of the transitioning separated shear layer that develops over the model. In this investigation, the effects of two aspects of the experimental setup, namely end plates and test-section blockage, on lowReynolds-numberairfoilexperiments areexploredthroughmeasurementsonaNACA0018airfoilmodelatachord Reynolds number of 100,000. The improvement in mean spanwise uniformity with end plates installed is quantified and demonstrates the importance of using end plates in two-dimensional airfoil experiments at low Reynolds numbers. Consistent with previous studies on the use of end plates on circular cylinder models, it is found that mean quantities measured on the center-span plane are least sensitive to end-plate spacing for spacings greater than roughly 7 times the projected model thickness. It is shown that the end-plate configuration affects vortex-shedding characteristics and disturbance amplification in the separated shear layer. Blockage effects are investigated by comparing measurements before andafter adaptive-wall test-section streamlining forsolid-blockage ratios between 4 and 8%. These blockage ratios are shown to cause errors in lift as high as 9% of the maximum lift and 3.5% in the wake vortex-shedding frequency. The results of this investigation can be used to estimate the effects of blockage on flow development in low-Reynolds-number airfoil experiments. It is demonstrated that a common blockagecorrectionmethodcanaccuratelycorrectliftmeasurementsformoderateblockagesinlow-Reynolds-numberairfoil experiments for conditions under which a separation bubble forms over the model.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 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".