Effect of the Unmixedness of Unburned Gases on the Pressure Fluctuations in a Dump Combustor
Bibliographic record
Abstract
Combustion instability is a serious obstacle for the lean premixed combustion of gas turbines and can even cause fatal damage to the combustor and the entire system. Thus, enhanced understanding of the mechanisms of combustion instability is necessary for designing and operating gas turbine combustors. In this study, in order to elucidate the instability phenomena, an experimental study was conducted in a rearward-step dump combustor with LPG and air. The fuel supply conditions and the mixing distances ( L fuel ) between fuel and air are used as experimental parameters to examine the effects of fuel modulation and unmixedness. The fluctuations of pressure, heat release, and equivalence ratio were measured by a piezoelectric pressure sensor and a high speed intensified charge coupled device (ICCD) camera, respectively. The unmixedness was measured by acetone laser induced fluorescence (LIF) at nonreacting flow because of stratification of the fuel in air. Various combustion modes occurred in accordance with the equivalence ratio and the fuel supply conditions. In the case of the fully premixed condition, the spatial fuel distribution inside the combustion chamber exists in a homogeneous state compared with the partially premixed condition, which leads to instant heat release, with relatively greater intensity for the chemiluminescence of the flame and higher amplitude of pressure fluctuations. On the contrary, in the partially premixed condition, the spatial fuel distribution exists in a heterogeneous state from the combustion chamber entrance, and the flame’s burnout or reignition progresses in accordance with the stratified distribution of fuel. The unmixedness of fuel and air leads to a relatively smaller intensity for the chemiluminescence of the flame and reduced amplitude of pressure fluctuations.
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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".