Theoretical-numerical comparison of water hammer generated in piping systems with variable diameter

Abstract

This study analyses and compares the value of the overpressure in a valve located downstream in a gravity system when there are variations in the geometric properties in the conduction (diameter changes). In  addition, the validity of the results obtained is analysed by comparing two methodologies: numerical modelling by finite elements and the application of theoretical expressions based on the method of celerity and equivalent length. For the numerical resolution of the equations a computational routine is developed in Matlab that allows representing the propagation of the pressure waves in the pipe. Then, the numerical model is defined considering all the conditions that the problem presents, and different cases are examined in which their variations in the geometric properties in the conduction are considering widenings and narrowing in different locations throughout the conduction. Finally, the study makes a comparison with the results of the maximum pressures obtained through the theoretical approximations.