Mitigation of PWR fuel assembly vibrations using bio-inspired nozzles
Bibliographic record
Abstract
Jet flows injected in a transverse flow need rapid and effective mixing for various applications ranging from medicine injection into bloodstreams to nuclear pressurized water reactors (PWRs). Inspired by marine organisms, spiral snails, and sharks, bio-inspired nozzles are proposed and experimentally investigated to explore their advantages in suppressing nuclear fuel assembly vibrations. It has been observed that a combination of axial flow and jet cross-flow causes vibrations of fuel rods and potential wear at spacer grid supports. Marine biomimetics is used to improve the mixing between the jet flow and surrounding fluid flows. Inspired by the structure of gastropod shells, a variable whorl spacing nozzle is proposed to induce a swirling jet flow to enhance the mixing rate with the flow inside the reactor cores. In addition, the smooth maneuverability of the sharks highlights the importance to include gill slits structure into nozzles. This work focuses on mitigating PWR fuel assembly vibrations using two biomimetic nozzles, a snail nozzle and a shark nozzle. These two nozzles are proposed to improve the mixing rate between the injected flow and the primary coolant flow, resulting in a reduced jet flow effect on fuel rods. A single-span mock-up PWR array is designed, fabricated, and instrumented to mimic the real nuclear fuel assembly. The array is experimentally tested under combined axial flow and jet cross-flow to investigate its dynamical behavior. Three different nozzles, a basic circular nozzle, a snail nozzle, and a shark nozzle, are tested. The research investigates the ability of the proposed marine biomimetic nozzles to suppress the vibration of the rod bundle by comparing the results from the three tested nozzles. The obtained results suggest that the proposed snail-inspired biomimetic nozzle is significantly better than the circular nozzle since it reduces rod bundle vibration by increasing flow mixing. A 50% reduction was achieved by implementing it instead of the circular nozzle. More importantly, the shark-inspired nozzle delays the critical jet flow rate, at which the unstable vibration occurs in the rod bundle, by 20%. In addition to delaying instability, a vibration amplitude reduction of 87.5% was obtained using the proposed shark-inspired nozzle compared to the circular nozzle. The results are promising for various applications including gas burners, combustion chambers, and chemical reactors for providing efficient and rapid mixing between two fluid streams.
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 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 | 0.000 |
| 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) | 0.001 | 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".