Numerical assessment of the tonal noise of Counter-Rotating Open Rotors at approach
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Bibliographic record
Abstract
A hybrid method combining a three-dimensional unsteady Reynolds-Averaged Navier–Stokes simulation of a cropped Counter-Rotating Open Rotors at approach conditions and an acoustic analogy either based on a time formulation, an advanced-time formulation of Ffowcs-Williams and Hawkings’ analogy, or on a frequency formulation, an extension of Hanson’s model to non compact chord length, has shown three main sources, the impacts of the front-rotor wakes on the aft-rotor, of the front-rotor tip vortex on the aft-rotor tip, and of the front-rotor hub horse-shoe vortex on the aft-rotor blade foot. Consequently, this study confirms that the aft-rotor is the dominant tonal noise source and has identified another potential noise source when the Counter-Rotating Open Rotors is installed caused by the strong tip vortex of the highly loaded cropped aft-rotor. The present rotor–rotor distance should not be reduced as the potential effect from the aft rotor is already felt on the front rotor. The influence of several numerical parameters including grid refinement, data sampling, and simulation length has been evaluated on both aerodynamic and acoustic performances.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it