Dynamic analysis of the pump system based on MOC-CFD coupled method

The dynamic characteristics of pump response to transient events were investigated by combining the Method of Characteristic (MOC) and Computational Fluid Dynamics (CFD) together. In a typical pump-pipeline-valve system, similar to the reactor system, the pump is treated as three-dimensional CFD model using Fluent code, whereas the rest is represented by one-dimensional components using MOC. A description of the coupling theory and procedure ensuring proper communication within the two codes is given. Several transient flow operations have been carried out. In the initial steady-state simulation, the coupled method could accurately find the operating condition of the pump when the valve is fully open. When the valve is closed rapidly, preliminary comparative calculations demonstrate that the coupled method is efficient in simulating the dynamic behavior of the pump and capable of getting detailed fluid field evolutions inside the pump. Deviation between the dynamic pump head and the value given by the steady-state curve at the same instantaneous flow-rate was established, and the cause of the deviation was further explained by the comparison of pump internal and external characteristics. Furthermore, it was found that the deviation grows with the severity of the transient. In addition, the effects of valve closure laws and pipe length on the pump dynamic performances were evaluated. All the results showed that MOC-CFD is an efficient and promising way for simulating the interaction between pump model and piping system. (C) 2014 Elsevier Ltd. All rights reserved.