Effects of Water Addition on Laminar Premixed Ethanol/Air Flame at Elevated Temperature and Pressure
Bibliographic record
Abstract
In this study, the effects of water addition on ethanol/air flames with high water content at elevated temperature and pressure are numerically investigated, and a novel correlation for their laminar burning velocity (LBV) is proposed based on experimental results. The dependence of the temperature and pressure exponents on thermodynamic parameters is numerically analyzed and considered in the new correlation to optimize the existing correlation. The fitting results of LBV correlations based on experimental measurements using a constant-volume method demonstrate that incorporating high-order and cross terms into the correlation enhances the overall performance, particularly under fuel-rich conditions where existing correlations exhibit significant discrepancies. The new LBV correlation of hydrous ethanol/air mixtures performs well over a wide range of elevated temperatures and pressures and agrees well with experimental data in the literature at high temperatures and pressures. The calculated LBV using the new correlation is also in good agreement with simulations using various mechanisms, except for fuel-rich mixtures with high water content, where the LBV is underpredicted by all mechanisms considered, suggesting further development of chemical mechanisms is needed. A sensitivity analysis suggests that under high water content, the dominant reactions of fuel-rich flames are different from those in stoichiometric and fuel-lean mixtures, highlighting that fuel-rich hydrous ethanol/air flames are very sensitive to water addition. The results also suggest that water addition leads to a reduction in the LBV. Both the burnt gas temperature and the peak heat release rate decrease with the water content, with a stronger influence on fuel-rich ethanol/air mixtures. Furthermore, the dilution effect of water addition constitutes the single largest effect in reducing the LBV, while chemical and thermophysical effects are found to be comparatively minor. The findings are helpful in understanding the fundamental combustion properties of hydrous ethanol and optimizing the LBV correlation under engine-relevant conditions.
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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".