Wind tunnel demonstration of galloping mitigation with a purely nonlinear energy sink
Bibliographic record
Abstract
Galloping is a critical type of flow-induced vibration (FIV) arising on power transmission lines, high rise buildings, pipe and cables bundles in the oil and gas industry. In this paper, we present a purely nonlinear energy sink (NES) that mitigates the galloping of a square prism. The NES is composed of a ball rotating freely in a circular track attached to the prism. The ball’s dynamics is coupled to that of the prism in a purely nonlinear way by inertia. We experimentally assess how this simple NES reduces the prism vibration by comparing the prism amplitude responses with and without the NES. A supplementary video presents these experiments, during which the NES ball exhibits different dynamics in three regimes; oscillatory, intermittent, and rotational. We characterize the ball behaviour and its effect on the prism response in each regime. The oscillatory regime appears at low flow speeds at which both the prism and the ball oscillate with small amplitude. The intermittent regime represents a transition mode within a small range of flow speeds and corresponds to a small jump in the vibration amplitude of the prism. The rotational regime appears at higher flow speeds, where the ball oscillates with relatively high angular speeds resulting in a strong modulated response of the prism. The design of the NES allows to easily vary its track dimensions to use a ball of different sizes and masses. Accordingly, we demonstrate the influence of the main NES parameters, which are the ball mass, NES track radius, ball friction, and radial clearance between NES track walls and the rotating ball, on both the prism response and the ball behaviour. The NES we present is directly amenable to mitigate other types of FIV.
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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 | 0.001 |
| 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 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".