Numerical study of effects of wall mass transfer condition for geometry factor

Prediction of geometry factor is one of the key elements for estimation of the flow accelerated corrosion (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 this study, the mass transfer coefficient is computed in 3 types of elbow pipe by using large eddy simulation (LES) at Re=45000 and is also measured experimentally with electrochemical method. In order to simulate the mass transfer coefficient, we adopt the analogy between mass transfer and heat transfer. The experimental measurement is conducted with the pipe of the test section made of nickel, in which the whole pipe surface acts as electrode. Geometry factor based on the heat transfer coefficient in LES agrees well with that measured in overall electrode condition and their maximum values are found to locate at the inner side of elbow outlet. (author)