Flame-Intrinsic Kelvin−Helmholtz Instability of Flickering Premixed Flames
Bibliographic record
Abstract
The flame-intrinsic Kelvin−Helmholtz (KH) instability, a self-oscillation of laminar flame fronts extending to the streamwise direction, was experimentally investigated using inverted conical premixed flames, and the governing parameters of flame flickering were deduced. We supposed that the flame flickering is caused by the KH instability, and the feature may be determined by which is dominant between the buoyancy-driven one taking place in the shear layer between hot products and ambient air and the flame-intrinsic destabilization because of the vorticity generation of flame fronts. For the distinction between the two, the former effect was excluded using a cylindrical quartz tube preventing the interaction with the ambient air and the latter was characterized by the flickering frequencies and wavelengths obtained by chemiluminescence signals and instantaneous images, respectively. Besides, laminar burning velocities were measured from the velocity normal to the flame front by the particle image velocimetry (PIV) method. From the dimensional analysis and physical considerations on an oblique plane flame front, it was estimated that the frequency will be determined by the flame structure and described by the modified Richardson number Ri f involved with the flame thickness and laminar burning velocity. From the experiments, it was revealed that the Strouhal number, dimensionless frequency, is proportional to Ri f 0.869 rather than the conventional Richardson number within the experimental conditions. This means that the flickering motions could be influenced by the flame-intrinsic KH instability described by the flame structure, in addition to the buoyancy-driven KH instability determined by the mixture velocity and length scale of burner geometry.
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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 | 0.001 | 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".