Effect of swirl flow generated by the combination of pipe elements on wall thinning phenomena

Flow accelerated corrosion (FAC) is the major pipe wall thinning phenomena in power plants. The management of pipe wall thinning has been carried out to pipe elements such as elbow, orifice, etc. of the piping system in power plants. In piping system, it is known that several pipe elements which are connected in series may generate swirl flow. Therefore the arrangement of pipe elements is considered to affect thinning phenomena seriously. So the behavior of this swirl flow is one of the major research targets to improve the accuracy of simulation codes. In Mihama Unit 3 pipe failure accident in 2004, it was pointed out the swirl flow caused by the piping layout might influence the thinning rate behind orifice. This study focuses on the behavior of main stream of swirl flow and reviews the effect to swirl number and turbulent kinetic energy distribution and the relation to pipe wall thinning. (author)