Development of the cooling technology on tru fuel pin bundle during fuel fabrication process:(2) High-speed PIV measurements in gap among fuel pins

A two dimensional and enlarged partial model was fabricated to measure detail flow distribution in gap among cylinders with a wrapping wire. The diameter of cylinders and wires is on (1:5) scale of an actual TRU fuel. The cylinder is modeled by a circular glass tube with an outer diameter of around 53 mm. A wire that has the outer diameter of around 5mm is mounted straight on the cylinder. The experiments were conducted by a high-speed particle image velocimetry (PIV) system and the time-resolved two-dimensional velocity data were obtained. Particles were illuminated by a laser sheet, which was irradiated from a circular tube containing an optical fiber a cylindrical lens and a prism, generated by a Nd-YLF laser operating at a wavelength of 527nm. The scatter light was captured by a high speed CMOS camera with 1024 × 1024 pixels and the images were acquired at 5000 frames/s. The test parameters were the wire mounting position on the cylinders and the average velocity at the wind tunnel exit. The time averaged velocity data were compared to the analysis and utilized for the turbulent model selection. Time-resolved data will be utilized to understand the flow structure in a narrow gap among cylinders with a wrapping wire.