Suppression of Acoustic Resonance in Rectangular Cavities Using Spanwise Control Cylinder
Bibliographic record
Abstract
Flow over cavities can be a significant source of noise in many engineering applications when a coupling occurs between the flow instabilities at the cavity mouth and one of the acoustic cross-modes in the accommodating enclosure. In this paper, a passive noise control technique using a spanwise cylinder located at the cavity upstream edge is investigated experimentally for two different cavities with aspect ratios of L/D = 1.0 and 1.67, where L is the cavity length and D is the cavity depth. The effect of both the location of the cylinder and its diameter on the flow-excited acoustic resonance is investigated in air flow with Mach number up to 0.45. This passive control technique is found to be effective in suppressing the acoustic resonance excitation when compared to the base case where no cylinder is attached. It is observed that using the optimum cylinder location and diameter reduces the acoustic pressure to less than 140 Pa, compared to the base case with values exceeding 2000 Pa. Moreover, a shift in the onset of acoustic resonance to higher velocities is observed. Localized hot-wire measurements of the free shear layer at the cavity mouth during the off-resonance conditions reveal that attaching a spanwise cylinder at the cavity upstream edge reduces the spanwise correlation of the free shear layer which, in turns, reduces its susceptibility to acoustic excitation. To further understand the interaction between the cylinder’s vortex shedding and the free shear layer at the cavity mouth, a numerical simulation of the flow field using a detached eddy simulation (DES) model has been carried out. The simulation shows that the suppression occurs due to a disturbance of the cavity shear layer by the vortex shedding from the cylinder which results in altering the impingement point at the downstream edge of the cavity, and thereby weakening the feedback cycle that controls the acoustic resonance excitation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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 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".