Flow-Induced Noise of Perforated Plates at Oblique Angles of Incidence
Bibliographic record
Abstract
This paper investigates experimentally the mechanism of tone generation from flow over a simplified model of a perforated plate. To simplify the geometry to two dimensions, a perforated plate is modeled by a series of rectangular slats with an adjustable gap width between them. This apparatus is tested at various angles of incidence and flow velocities, to identify the conditions favorable to the production of tonal noise. The results of this research are presented in two main parts. First, the acoustic response of the test plates is documented by means of microphone measurements. It is found that for an angle of incidence between 5 and 30 degrees and a flow velocity of 10 to 30 m/s, tonal noise is produced. Outside of this range of angles, the produced sound is broadband. In the second part, phase-locked particle image velocimetry (PIV) is used to study the flow field. It is found that vortices form in the free shear layer of the gaps between the slats. These vortices impinge on the side of the downstream slat and are then ejected through the gap to the backside of the plate. As these vortices leave the edge of the downstream slat, counter rotating vortices are shed in sympathy with the incident vortices. Vortex pairs are therefore periodically shed which are thought to be the cause of tone generation.
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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".