Effect of Fuel Nozzle Geometry on Swirling Partially Premixed Methane Flames
Bibliographic record
Abstract
Abstract This paper presents an experimental study of the effect of fuel nozzle geometry on swirling partially premixed methane flames, where the focus is put on the ensuing flowfield and its role on coherent structures' suppression. The burner consists of a central interchangeable fuel nozzle surrounded by a swirling co-airflow where both discharge into a short mixing tube. The nozzle geometry is classified into two groups, namely, single- and multi-orifice nozzles. The swirling motion of the co-airflow is produced using a radial-type swirl generator with a swirl number of 1.15. The flowfield characteristics and coherent structures are documented using particle image velocimetry (PIV). Flame front dynamics are captured using Mie scattering technique. Quantitative laser sheet (QLS) is used to qualitatively shed light on the mixing characteristics downstream of the mixing tube exit, and laser Doppler velocimetry (LDV) is used to extract the coherent structures' peak frequency from the power spectra. The results revealed that the fuel nozzle geometry significantly affects the mean flowfield, mean, and root-mean-square (RMS) of the flame front location, flame front asymmetry, and coherent structures' amplitude. Higher spread rate and faster decay caused by single-orifice nozzles inside the mixing tube result in divergent flames with higher degree of flame front asymmetry downstream of the mixing tube exit. On the other hand, multi-orifice nozzles mitigate coherent structures, enhance mixing, and hence, promote the most appropriate conditions for coherent structures' suppression.
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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) | 0.000 | 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".