Relatively a large number of pipe failures in a nuclear power plant occur in a multi-component region such as the bends, the orifices and so on. Especially, it has been reported that FAC (Flow Accelerated Corrosion) frequently occurs in a multi-elbow. In this study, therefore, a complex flow structure in a s-shaped dual elbow is observed by using a PIV system to clarify the flow structure. The diameter of the elbow D is 56mm and the curvature radius rate y (=R/D,where Re is a curvature radius) is 1.5. A f...
英字タイトル:
Clarification of complex flow structure in dual elbow

This work addresses LDI (Liquid Droplet Impingement) accompanied with pipe wall thinning in nuclear and thermal power plant s. In order to clarify the factors that affect the wall thinning, the structure of supersonic two-phase flow after an orifi ce is visualized with a digital video camera. The visualization experiment proves that the droplets impinges the pipe wall shortly after the orifice and that the amount of water droplets that passes through the orifice is the important parameter....
英字タイトル:
Evaluation of Liquid Droplets Impact Erosion in downstream areas of an orificecaused by supersonic two-phase flow

Pipe wall thinning is one of the most important technical problems in nuclear power plants. For example, the wall thinning occurs by two-phase flow at both the orifice downstream and the first elbow located downstream after the orifice. In this study, a visualization experiment was conducted in order to clarify the detailed mechanism of the wall thinning by erosion (LDI is expected) in the piping system consisting of an orifice, a straight pipe and an elbow.In the experiment a strong pressure at the down ...
英字タイトル:
Analysis (2) of Liquid Droplets Impact Erosion at the orifice downstream area caused by supersonictwo-phase flow