Flow structure of high Reynolds number flow in a dual-elbow piping simulating cold-legs of JSFR

Takamura, Hiroyuki*; Ebara, Shinji*; Kaneko, Tetsuya; Yamano, Hidemasa   ; Hashizume, Hidetoshi*

Flow visualization experiment with 2D-PIV in a dual elbow system simulating the cold-leg piping of the JSFR was performed varying Reynolds number from 0.310 to 1.010. The tested piping has two short elbows which are three-dimensionally connected with a straight pipe. In the dual elbow system, separation vortices are shed from the separated region like a single elbow one. These vortices flow by the inrados of the second elbow and its lower stream. The post-critical regime of the dual elbow flow appears when Reynolds number is larger than about 0.510, as with the single elbow system.