Numerical Study of Self-Excited Oscillations and Aeroacoustic Sources of Jet Flows in High Temperature Gas Reactor Cores
Bibliographic record
Abstract
Abstract High-temperature gas-cooled reactors (HTGRs) improve thermodynamic efficiency due to high operating temperatures and the use of chemically inert gas coolants promotes the longevity of the reactor components. However, the use of high speed gaseous coolants in such reactors can face flow- and acoustic-induced vibration issues. Previous operational experience in gas-cooled reactors have shown a history of these issues, ultimately resulting in economic losses due to project delays, unscheduled maintenance, and reactor shutdowns. Despite the advantages of HTGRs, limited data on the complex flow-sound-structure interactions in gas-cooled reactors complicate the design of future systems. Given the difficulties of creating comprehensive experimental test facilities, high-fidelity simulations have emerged as essential tools. In this study, the self-excited fluid-resonant conditions of a subsonic jet exiting the HTGR reactor core and impinging on the reactor plenum was numerically investigated. Focusing initially on a two-dimensional planar jet with impingement length-to-jet width ratios (L/H) of 7 and 10, a fully coupled, compressible CFD simulation was performed. The resulting flow field was post-processed to extract the acoustic field, and Howe’s integrand identified aeroacoustic energy exchange regions. It was found that the simulations captured the self-excited oscillations of an impinging planar jet at the different L/H. The Strouhal number based on the jet width (StH) closely matched the Rossiter model predictions and experimental data, while three anti-symmetric vortex cores in the vorticity field confirmed oscillations at the n = 3 jet-stage. Helmholtz decomposition revealed high acoustic particle velocities at the jet inlet and impingement region, indicating significant aeroacoustic energy exchange in these regions. The preliminary findings of this study demonstrate that CFD can be a valuable tool for investigating fluid-resonant conditions in HTGR systems.
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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 | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 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".