Numerical and Analytical Estimation of the Hydrodynamic Coefficients of a Radial Seal under Whirling Vibrations
Bibliographic record
Abstract
Abstract Turbulent leakage flow passes through the radial seals and spiral cases of turbine runners. A small deviation of the runner changes the radial seal flow, inducing a strong pressure gradient. Reaction fluid forces act on the runner which hence whirls. These forces are modeled by dynamic force coefficients on the shaft-line dynamics. We determine those coefficients to predict whirl vibrations. The radial and tangential forces are written as quadratic and linear polynomials of the whirl frequency. The polynomial coefficients correspond to the runner dynamic coefficients. A computational fluid dynamics (CFD) simulation computes these forces for different whirl frequencies of a disk-like structure. Harmonic analyses on a vibroacoustic finite element model (FEM) yield the same forces, which are interpolated to obtain the dynamic coefficients. These numerical models are compared with an analytical potential flow theory model for a plain annular seal geometry. CFD considers more physics than the other methods as it includes the fluid shear. Parametric studies on a clearance-and-side-chamber geometry highlight that hydrodynamic coefficients vary with runner frequency, axial mass flow rate, runner angular frequency and radial seal clearance. The resulting runner dynamic coefficients improve the shaft line analysis, as more physical phenomena are considered on a real geometry.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".