Effect of Internozzle Spacing on Lean Blow-Off of a Linear Multinozzle Combustor
Bibliographic record
Abstract
This paper studies the effect of internozzle spacing on the lean blow-off of a linear combustor array. The combustor’s lean operability limit did not have a monotonic relationship with internozzle spacing; the configuration with the intermediate nozzle spacing was the most stable. Simultaneous multi-kHz repetition-rate OH planar laser–induced fluorescence (OH-PLIF) and stereoscopic particle image velocimetry (S-PIV) measurements were used to examine the fluid and flame kinematics during the transient blow-off process. Although the blow-off process of any individual nozzle—wherein local extinction led to mixing of cold fluid into the central recirculation zone (CRZ), leading to further extinction—was similar regardless of the internozzle spacing, the presence of adjacent flames influenced both the global and local kinematics. Cross-nozzle flame transport through convection of burning fluid was found to help stabilize the flames in the multinozzle configurations, but could not explain the improved stability of the intermediate spacing case. Furthermore, the intermediate spacing configuration was able to sustain attached flames with greater fluid dynamic strain rate than the other configurations, indicating that it was more resistant to local extinction, ultimately leading to total blow-off. The configuration with the intermediate nozzle spacing had the largest CRZ. A Damköhler number based on the CRZ axial length and bulk velocity at blow-off was relatively constant across the configurations, indicating that a large CRZ provides robustness against the blow-off process. These results demonstrate the complex interplay between fluid dynamics, geometry, and stability of combustion systems.
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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 | 0.000 | 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 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".