Abstract
Fibre Bragg grating (FBG) grid sensors are an underexplored technology with potential to benefit nuclear thermal hydraulics experiments. This paper presents a new FBG grid sensor consisting of 38 FBGs across 8 flow-crossing chords. Using this sensor, experiments determined for the first time that an FBG grid can detect large air bubbles rising in standing liquids—demonstrated in both columns of water and 20W50 automotive oil. The instrument’s sensitivity was quantified by comparing its measurements to high-speed camera recordings. Analysis of Bragg wavelength shift timings on each chord enabled the surface of a bubble to be reconstructed using the air–oil data. Finally, the increase in Bragg wavelength when bubbles interact with the FBG grid suggests a variant sensing principle different from that reported in the literature for FBG grids in flowing liquids.
| Original language | English |
|---|---|
| Article number | 52 |
| Pages (from-to) | 1-19 |
| Number of pages | 19 |
| Journal | Journal of Nuclear Engineering |
| Volume | 6 |
| Issue number | 4 |
| Early online date | 30 Nov 2025 |
| DOIs | |
| Publication status | E-pub ahead of print - 30 Nov 2025 |
Keywords
- multiphase flows
- fibre Bragg gratings
- flow characterisation
- nuclear thermal hydraulics
- fluid dynamics