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Kimura, Nobuyuki; ; ; ; Kamide, Hideki; Tokuhiro, Akira; Hishida, Koichi
JNC TN9400 2000-057, 60 Pages, 2000/05
ln experimental study for the thermohydraulics of fast reactor, a simple experiment with fine measurement has been desired for understanding of phenomena and for verification of computer code rather than mockup experiments of large scale. For such purposes quality of experimental data must be improved. ln the velocity measurement, instantaneous velocity profile will have great advances for the understanding of phenomena and for the verification of computer code. ln this report two methods of the velocity profile measurement are discussed; one is ultrasound Doppler velocimetry (UDV) and the other is particle image velocimetry (PIV). These methods were applied to water experiments. The UDV was applied to pipe flow, planer jet, and the inter-wrapper flow which is seen in the gap region between subassemblies of fast reactor core. Cross check with laser Doppler velocimetly showed proper measurement of the UDV. Problems including the application to sodium experiments are also discussed. The PIV was also applied to the inter-wrapper flow. For the application to complex flow geometry, noise reduction method was developed to improve the measurement accuracy.
Tokuhiro, Akira; Kimura, Nobuyuki;
JNC TN9400 2000-014, 86 Pages, 1999/06
Experiments were performed using the WAJECO facility to investigate the thermohydraulic mixing of multiple jets flowing out of a LMFBR core. Mixing is the root of the thermal striping problem. The multiple jets are typically at different velocities and temperatures and may induce thermal stresses upon components they impinge. In our study we modeled the mixing of three vertical jets, the central at a lower temperature than the two adjacent jets at equal temperatures. The jets are quasi-planar. The parameters were the average exit jet velocities (Uo,av) and the temperature difference between the "cold" and "hot" jets (Thc=Thot-Tcold). Measurements of the liquid velocity, initially using laser Doppler velocimetry (LDV) and later ultrasound Doppler velocimetry (UDV), for both our reference single-jet and the triple-jet configuration, comprised Phase I of the experiments (up to 1994). Two reports (TN9410 96-181 and TN9410 96-296; in Japanese) reported on the hydraulic and heat tra