Effects of Simplified Platform Overlap and Cavity Geometry on the Endwall Flow: Measurements and Computations in a Low-Speed Linear Turbine Cascade
Bibliographic record
Abstract
Incorporating the platform overlap and endwall cavity into the early stages of turbine CFD analyses is desirable from the perspective of accurately capturing the near endwall flow features. However, the overlap and cavity geometry increase the complexity of the computational domain making CFD meshes more difficult to generate and the CFD solutions more resource intensive. Thus, geometric approximations are often made to simplify the CFD analysis. This paper examines, experimentally, the secondary flows of a linear turbine cascade with three different platform overlap geometries, two of which incorporate geometric simplifications. These are then compared with the corresponding computations. Experimental measurements were collected using a seven-hole pressure probe at a plane located 40% of the axial chord downstream of the trailing edge. Steady-state computational predictions were performed using ANSYS CFX 12.0 and employed the SST transition turbulence model. The experimental results show that the presence of an upstream rim-seal creates a stronger passage vortex, relative to a flat endwall, resulting in larger integrated losses as well as higher levels of secondary kinetic energy and streamwise vorticity. Subtle differences in the strength of the passage vortex and the associated losses are observed for the simplified geometries in both the measured and predicted results. By examining the details of the cavity flow, a recirculation zone is identified which energizes the formation of the passage vortex. The effect of the recirculation zone may be attenuated or intensified by the rim-seal geometry. The paper concludes by addressing the validity and usefulness of the proposed platform overlap simplifications in design-oriented computations.
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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".