Investigation of Transient Wave Behavior in Water Pipelines with Blockages

Partial blockages commonly exist in water pipelines due to various physical, chemical, and biological processes, including sediment, corrosion, and biofilm. The formed blockages can result in low flowing capacity, additional energy loss, and water quality deterioration during the water conveyance process, such as urban water supply and drainage systems. This paper presents an investigation on the interaction of transient pressure waves with pipe-wall roughness and blockages in water pipelines. The analytical expression of wave propagation in a pipeline with rough blockages is firstly derived by multiscale wave perturbation analysis for transient pipe flows. The analytical results and analysis demonstrate that the wave scattering (amplitude damping and phase shifting) is dependent on the relationship between the incident wavelength and the correlation length of roughness-blockage disorders in the pipeline. The relative importance of pipe-wall roughness friction and pipe blockage constriction to wave scattering in terms of wave envelope attenuation and wave phase change is then investigated based on the analytically derived results. Two dimensionless parameters, which are functions of the properties of incident waves, pipe-wall roughness, blockage severity and range, and internal fluid conditions, are formulated to characterize such relevance and importance. For validation, the analytical results are compared with experimental data collected in this study based on a laboratory experimental test system. Finally, the key results and findings of this study are discussed for their applicability and implication to transient pipe flow modeling and pipeline condition assessment in practical applications.