Large Eddy Simulation for a Deep Surge Cycle in a High-Speed Centrifugal Compressor With Vaned Diffuser
Bibliographic record
Abstract
This paper presents a computational study for a high-speed centrifugal compressor stage with a design pressure ratio equal to 4, the stage consisting of a splittered unshrouded impeller and a wedged vaned diffuser. The aim of this paper is to investigate numerically the modifications of the flow structure during a surge cycle. The investigations are based on the results of unsteady three-dimensional, compressible flow simulations, using large eddy simulation (LES) model. Instantaneous and mean flow field analyses are presented in the impeller inducer and in the vaned diffuser region through one surge cycle time intervals. The computational data compare favorably with the measured data, from the literature, for the same compressor and operational point. The surge event phases are well detected inside the impeller and diffuser. The time-averaged loading on the impeller main blade is maximum near the trialing edge and near the tip. The amplitude of the unsteady pressure fluctuation is maximum for the flow reversal condition and reaches values up to 70% of the dynamic pressure. The diffuser vane exhibits high-pressure fluctuation from the vane leading edge to 50% of the chord length. High-pressure fluctuation is detected during the forward flow recovery condition as a result of the shock wave that moves toward the diffuser outlet.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".