Aeroacoustics of Opposing Planar Air Jets
Bibliographic record
Abstract
The self-excited response of two opposing planar air jets is experimentally examined as a function of both flow velocity of the jets, as well as the impingement distance, i.e. the distance z between them. This initial study is performed for a single jet thickness of h = 2 mm and a spanwise aspect ratio of 50. Two sets of experiments have been performed, with the first set of measurements having been obtained over a range of impingement ratios from z/h = 7 to z/h = 130 for several moderate Mach numbers (M = 0.44, 0.58 & 0.73), whereas the second set of measurements has been performed by varying the jet Mach number at fixed impingement ratios. The opposing planar jets are found to produce intense acoustic tones over the entire range of impingement ratio and flow velocity examined in this study, showing robust oscillation behavior even for very large distances between the jets. Acoustic tone frequency has been found to increase linearly with the jet exit velocity at constant impingement ratio and to decrease with the impingement distance at constant jet velocity. The flow field over the oscillation cycle has been investigated by means of phase-averaged PIV measurements technique, which has shown that the high noise levels and acoustic tones are produced by a pronounced flapping oscillation of the opposing jet columns.
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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 | 0.002 |
| 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".