Non-equilibrium condensation modeling of CO2 nozzle flow under subcritical and supercritical conditions
Bibliographic record
Abstract
Turbomachinery is crucial in transcritical CO2 heat pumps and supercritical CO2 Brayton cycles. During the internal transcritical expansion process, non-equilibrium condensation can occur, leading to droplet formation, which reduces turbomachinery efficiency and may damage the blades. Currently, non-equilibrium condensation calculations face inaccurate predictions of condensation shock waves and downstream pressures. To investigate the influence of various factors on the accuracy of non-equilibrium condensation numerical simulation, this study examines the effects of nucleation models, droplet growth models, and turbulence models. The Eulerian–Eulerian source term model is employed to compare and study the non-equilibrium condensation within a CO2 Laval nozzle under subcritical and supercritical inlet conditions. The results indicate that different nucleation models directly affect the numerical accuracy of the nucleation location and the condensation shock wave, with minimal impact on the pressure distribution downstream of the throat. Besides, different droplet growth models have little effect on the numerical accuracy of nucleation location and the downstream pressure distribution. The large eddy simulation has a significant impact on numerical accuracy, with a larger pressure jump and better experimental agreement for downstream pressure distribution. These findings provide guidance for the further development of non-equilibrium condensation models.
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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".