FLOW-INDUCED VIBRATION OF A LARGE-DIAMETER ELBOW PIPING IN HIGH REYNOLDS NUMBER RANGE; RANDOM FORCE MEASUREMENT AND VIBRATION ANALYSIS

The design of Japanese large-scale sodium-cooled fast reactor requires increase in primary coolant velocity and enlarging the diameter of piping, so that a flow-induced vibration for this piping with a short radius elbow should be considered. To evaluate this vibration, flow-induced-vibration tests have been carried out using two kinds of 1/3-scale elbow test sections, which simulate a hot-leg piping. In the flow visualization test using the test section made of acrylic resin, pressure fluctuations and correlation lengths have been obtained with pressure sensors. In the flow-induced-vibration test using the test section made of stainless steel, natural frequencies, mode and random vibration response have been measured. Random vibration stress on the test section has been calculated from the power spectrum densities of pressure fluctuations and their correlation lengths by a vibration analysis method based on random vibration theory. This method has been verified by comparison with the vibration stress obtained from the flow-induced-vibration test.