Improving Micro-Mixing Combustion Stability Using Fuel Preheating and Product Recirculation
Bibliographic record
Abstract
Abstract Micro-mixing is a promising combustion approach due to its inherent safety against flashback and autoignition, with multiple studies having demonstrated low NOx levels in the order of premixed combustion. Previous work has extended the operating limits of micro-mixing combustion to the design requirements of highly recuperated gas turbines, demonstrating low NOx performance at inlet temperatures of up to ∼1000 K with hydrogen and hydrocarbon-based fuels such as propane, natural gas, and jet fuel. Due to its highly reactive nature, micro-mixing combustion of hydrogen is very stable, but instabilities were observed with hydrocarbon-based fuels when operating near premixed levels of NOx due to their slower reaction rates, indicating that a trade-off exists between NOx emissions and combustion stability. This paper presents the experimental results of a new micro-mixing injector designed to improve combustion stability by 1) increasing the recirculation of combustion products to the flame zone, and 2) preheating the fuel by heat transfer from the combustion products to the injector. Although this configuration is still susceptible to instabilities, their amplitudes are much lower, with levels of < 10 dB compared to ∼20 dB for the standard micro-mixing injector. NOx emissions are similar for both injector configurations, indicating a better trade-off between combustion stability and emissions when operating near the levels of perfectly premixed combustion for the new injector configuration.
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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".