ICONE19-43712 STUDY ON FLOW INDUCED VIBRATION EVALUATION FOR A LARGE SCALE JSFR PIPING : (3) PRESSURE FLUCTUATION CHARACTERISTICS IN 1/3 SCALE HOT-LEG PIPING EXPERIMENTS UNDER DEFLECTED INFLOW CONDITIONS DUE TO UIS STRUCTURES

Abstract

In this study, flow-induced vibration experiments were performed using a test facility that simulates the hot-leg (HL) piping with a 1/3-scale model to investigate flow patterns and fluctuating pressures on the pipe wall. The complicated flow in the upper plenum of the reactor vessel goes into the HL piping. One of the flows entering the HL which could significantly influence a flow-induced vibration is deflected flow. This paper describes the 1/3-scale experimental results under the deflected-flow conditions at the inlet of the HL. To simulate the flow conditions, a part of an upper internal structure was modeled in the test facility to generate deflected flow. The parameters were an intensity of deflected flow controlled by the opening ratio of the #1 baffle plate of the upper internal structure. Quantitative investigation was conducted in terms of the influence of the deflected flow on the size of the flow separation, the flow velocity distribution, and intensity of fluctuating pressure on the pipe wall. It could be observed that the region of the flow separation was deformed by the deflect flow. In the case of the 0% opening, the tendency of the velocity distribution near the flow separation and the shape of flow separation differ from those in the other cases of opening.