Effect of spacing ratio on unsteady flow characteristics of tandem andside-by-side circular cylinders in cross-flow during self-excited acousticresonance
Bibliographic record
Abstract
Circular cylinders are commonly used in various industrial applications such as civil structures, marine pipelines, antennae, energy harvesting systems, and heat exchangers.When the Reynolds number is high enough, periodic vortex structures known as vortex shedding form in the wake of the cylinders.This phenomenon induces fluctuating forces at the vortex shedding frequency due to its oscillatory nature.In enclosed systems like heat exchangers, if the vortex shedding frequency is close to the frequency of an acoustic resonant mode, acoustic resonance may occur if the flow energy is sufficient to overcome the acoustic damping capacity.This can lead to the initiation of self-excited acoustic resonance.During self-excited acoustic resonance, a feedback mechanism is initiated where the vortex shedding process acts as an aeroacoustic sound source, which excites an acoustic standing wave, and in-turn improves the vortex shedding process.During self-excited acoustic resonance, severe tonal noise is generated, potentially reaching sound levels of 175 dB in heat exchanger tube bundles.These noise levels can cause excessive vibrations in surrounding equipment, disrupt operation, and create hazardous work environments for nearby workers.The intricate nature of the flow-acoustic coupling in heat exchanger tube bundles can only be understood if the flow-sound interaction mechanisms from cylinders in different arrangement, such as tandem and side-by-side cylinders, is investigated.Thus, this study aims to provide a better understanding of the effect of the center-to-center longitudinal (L/D) and transverse (T/D) spacing ratio between circular cylinders in tandem and side-by-side arrangements on the unsteady flow characteristics and how they change when self-excited acoustic resonance is triggered.The study focuses on longitudinal spacing ratios (L/D) ranging from 1.5 to 4.5 for tandem cylinders, and transverse spacing ratios (T/D) ranging from 1.2 to 5 for side-by-side cylinders, as these ratios correspond to different flow regimes found in these arrangements.Acoustic pressure measurements are employed to analyze the aeroacoustic response of the cylinders.Particle Image Velocimetry (PIV) is utilized to visualize the flow field before self-excited acoustic resonance, while Proper Orthogonal Decomposition (POD) analysis is used to capture the periodic flow structures near the cylinders.Phase-locked PIV measurements are conducted during self-excited acoustic resonance to obtain flow field data at specific phases in the acoustic pressure cycle.,
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How this classification was reachedexpand
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 | 0.001 |
| 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) | 0.000 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, 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".