Unveiling the impact of pipe materials on water hammer in pressure pipelines: an experimental and numerical study

Abstract

Water hammer (WH) is a phenomenon characterized by the rapid opening or closing of valves or pumps in pipelines, resulting in a disruptive noise, intense vibrations, and potential damage to pipes, fittings, structures, and even human safety. While WH arresters are commonly employed to mitigate this issue in smaller plumbing systems, alternative solutions are required for larger applications like power plants. Researchers have proposed the utilization of pipe materials with a low modulus of elasticity in areas prone to WH events, as these materials possess the capability to absorb a significant portion of the resulting vibrations. This study focuses on investigating the influence of pressure and strain induced by the WH phenomenon. Experimental data collected from measurements using a specially designed test rig, as well as numerical and dimensionless analyses applied to the same rig, are employed to examine this effect. The experimental and numerical investigations encompass a range of flow rates and pressures. Five pipe materials, namely Galvanized steel, Copper, uPVC, PPr, and GRP, were selected for evaluation. The results indicate a deviation between the numerical and experimental results of WH frequency which can be explained from the pipeline rigidity. A Fast Fourier Transform (FFT) analysis was performed to analyze the frequency components of the pressure transients resulting from water hammer events in the different pipe materials. The results indicate that pipe materials with lower elastic modulus, such as PPr and uPVC, exhibit reduced WH effects compared to materials with higher elastic modulus, such as steel. This research highlights the importance of selecting appropriate pipe materials for pressure pipelines in order to mitigate the dangers associated with WH. The results of the FFT analysis revealed distinct frequency responses for each material, illustrating how their unique viscoelastic properties affect the transient behavior.