Study on flow-induced-vibration evaluation of large-diameter pipings in a sodium-cooled fast reactor, 2; A Large-Eddy Simulation of turbulent flow in a short-elbow pipe

Eguchi, Yuzuru*; Murakami, Takahiro*; Ohshima, Hiroyuki; Yamano, Hidemasa   ; Kotake, Shoji

The unsteady turbulent flow in a short-elbow pipe to be employed in a Japanese sodium-cooled fast breeder reactor was computed to examine the fundamental features of the flow, especially, pressure fluctuation to cause unsteady fluid force on the pipe. An FEM-based large-eddy simulation code, named SMART-fem, was used for the computation. The results at Re=3.210 and 1.210 show that two separation regions exist on the inner urvature of the elbow around 45-degree (middle of elbow) and 90-degree (end of elbow) positions. The statistical quantities of pressure fluctuation such as deviation, skewness and flatness were computed and analyzed, showing that there exist two symmetric regions of significant pressure fluctuation on the wall of inner curvature of the elbow. It has turned out that the pressure loss coefficient of the elbow pipe agrees well among the computation, experiment and authoritative reference data.