Comprehensive CFD analysis of base pressure control using quarter ribs in sudden expansion duct at sonic Mach numbers
Why this work is in the frame
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Bibliographic record
Abstract
This study aims to assess the effect of rib size, shape, and location in a suddenly expanded flow at sonic Mach number. Flow from a converging nozzle is exhausted into a larger area of duct diameter of 18 mm. The geometric parameters considered are the area ratio, duct length, rib radius, and inertia parameters, which are considered the level of expansion at critical Mach number. In the present study, duct lengths were from 1D to 6D, rib radii considered were 1 mm to 3 mm, and rib locations were 0.5D, 1D, 1.5D, 2D, and 3D. Results show that when the ribs are placed near the reattachment point with a 3 mm radius, they are efficient and capable of reducing the suction in the recirculation zone and the base pressure, which was lower than the ambient pressure in the absence of ribs, is assorted larger than the back pressure. If the requirement is to equate the pressure at the base to ambient pressure, then a 2 mm radius is the right choice. Furthermore, the 1 mm rib cannot reduce the suction in the base region, and base pressure remains sub-atmospheric for the entire range of rib locations, as well as the NPRs of the present study. When the orientation of the ribs is changed, and the flow interacts with the flat surface instead of the curved surface, there is a marginal change in the flow pattern, and there is no significant change in the base pressure values.
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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 | 0.001 | 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 it