Numerical study on subsonic-supersonic Laval nozzle
Bibliographic record
Abstract
Abstract Because subsonic-supersonic Laval nozzles are widely used in many fields, the flow characteristics of the subsonic-supersonic Laval nozzle are studied by numerical simulation. First, the MacCormack scheme is used to discrete the non-conservation and conservation forms of the governing equations of the flow in the subsonic-supersonic Laval nozzle. The flow states inside the nozzle in both formats are then compared. The results show that the numerical results of the two schemes converge well. The variation of the fluid velocity and outlet pressure is more pronounced in the non-conservative form. For the conservation form, the error of the mass flow rates at different positions is constant and acceptable, which is about 1%. For the non-conservation form, the error at different locations within the nozzle is different, reaching a minimum error at the throat. In addition, studies on grid length have demonstrated that the finer the grid, the more accurate and stable the results Moreover, for the subsonic, supersonic isentropic flow in the quasi-one-dimensional nozzle, the Mach number and velocity become larger along with the nozzle. In contrast, other variables such as pressure and temperature become smaller. There is a subsonic region in front of the throat and a supersonic region behind the throat. The Mach number of the nozzle exit can be very high. Finally, the study reveals the internal flow state of the subsonic, supersonic nozzle, which can provide theoretical reference for the application of the nozzle.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".