Pitch–Heave Symmetric Stall Flutter of a NACA0012 at Transitional Reynolds Numbers
Bibliographic record
Abstract
Large-amplitude limit cycle oscillations (LCOs) in one degree of freedom (1DOF) in pitch and 2DOFs in pitch–heave induced by stall flutter are explored experimentally on a NACA0012 wing. Because stall flutter is mainly understood from the point of view of dynamic stall, it has been generally agreed that the oscillations associated with negative aerodynamic damping occur about a large angle of attack. In contrast, symmetric oscillations about the origin are reported in this work, where the amplitude of oscillation, ranging from 30° to about 50°, is limited by flow separation. The elastic axis is fixed at . The airspeed is varied over a range of Reynolds numbers extending from to . For experiments in 2DOFs, the stiffness in pitch is kept constant, whereas the heave stiffness is changed to cover a range of frequency ratios, . Except for cases with frequency ratios close to one, the introduction of the DOF in heave does not significantly affect the LCO dynamics. It is determined that the stall flutter observed is fundamentally a 1DOF problem in pitch, whereby the pitch motion drives the heave motion. Nonetheless, the work done by the lift force (on the heave) is larger than the work done by the aerodynamic moment (on the pitch).
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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 | 0.000 |
| 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".