A Theoretical and Experimental Investigation on Ejector Acoustics and Ejector Silencer Design
Bibliographic record
Abstract
Ejectors are common devices used across many industries, however, they are often plagued by the presence of low frequency pressure pulsations causing both broadband and tonal noise. This thesis presents a theoretical and experimental investigation into the acoustics of an ejector-silencer combination with the emphasis placed on silencer design. More specifically, the noise generated by the jet, the diffuser and natural modes is explained and estimated. The noise generation mechanisms of impingement tones and edgetones are presented but accurate predictions are found to be hard to make. An outline of the experimental facility is followed by the mechanical, acoustical and aerodynamic design details of the approximately 70:1 ejector scale model. A detailed analysis on the primary nozzle control and calibration is presented before beginning an aerodynamic and acoustic characterization of both the ejector and the wind tunnel facility. From experimentation, it is found that the placement of a perforated cone in front of the solid cone is beneficial in reducing the noise generated without overly affecting the entrainment ratio. Other configurations tested tend not to be as acoustically effective or to decrease the entrainment ratio below an acceptable level. Experiments prove that the low frequency noise generated by the ejector is mainly caused by natural mode excitation.
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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 | 0.000 |
| 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 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".