エルボ管におけるFAC減肉速度と物質移行係数の評価について

Abstract

Flow accelerated corrosion (FAC) is one of the causes for wall thinning mechanisms in carbon steel pipes. Prediction of geometry factor is the key elements for estimation of FAC. Geometry factor is defined as the ratio of wall mass transfer coefficient in the piping systems such as elbow to that in a straight pipe. In order to simulate the mass transfer coefficient, we adopt the analogy between mass transfer and heat transfer. In this study, geometry factor of the elbow pipe is computed by using large eddy simulation (LES) for various Prandtl number and Reynolds number. When Prandtl number is close to unity, geometry factor changes depending on Prandtl number. However, as Prandtl number increases sufficiently, geometry factor becomes independent of Prandtl number. As the Reynolds number increases, geometry factor of the INSS elbow decreases, with reduction of the area in which large geometry factor is observed.