Numerical Simulation on Water Hammer Phenomenon for Single Feedwater Line

Abstract

Since the feedwater line is susceptible to water hammer phenomenon, the effect of water hammer on single feedwater line was numerically analyst using the PIPENET software package. The main devices of the single feedwater line include a feedwater pump, a feedwater isolation valve, a feedwater control valve, and a feedwater check valve. Calculation and analysis of the water hammer were carried out based on the feedwater isolation valve which was instantaneously closed with various diameters and lengths and also different Poisson ratio and elastic modulus of the feedwater line. The results showed that the water hammer pressure and load in the lines reached the maximum at the moment of the feedwater isolation valve closing. After a long period of time, the final pressure of the lines was maintained at the initial pressure value and the final water hammer load tended to zero. The larger diameter and the shorter length of the feedwater lines would obtain the less water hammer pressure and load. The smaller the length–diameter ratio was, the lesser the water hammer pressure and load will be. When the length–diameter ratio reached a certain value, the water hammer load showed a fluctuation trend. The larger Poisson ratio and elastic modulus would obtain the higher peak values of water hammer pressure and load, but different Poisson ratios and elastic modulus of common materials had little effect on water hammer pressure and load. These calculation results in this work can provide some technical support for the diameter and material selection and length arrangement of the feedwater lines and also offer certain design basis for the stress analysis of the feedwater system.