Experimental Study of Flow-induced Pressure Fluctuations in Horizontal Straight Pipes with Single- and Two-phase Flow

Pressure fluctuations caused by multiphase flow within pipes are significant factors that can lead to severe damage to piping infrastructure and result in noise emissions from the pipelines. This study presents a fundamental investigation into flow-induced pressure fluctuations and their distribution on pipe walls caused by single-phase and two-phase flows in a straight pipe. Experiments were conducted using a flow test loop to measure pressure fluctuations under varying flow velocities and water fractions. Simplified one-dimensional numerical modeling was also employed to examine the effects of a reservoir tank on pressure magnitudes and distributions within the piping system. The results demonstrated that pressure fluctuations in single-phase flow are primarily influenced by flow velocity, while in two-phase flow, fluctuations are significantly affected by water fraction and free surface deformations. Open-loop and closed-loop conditions were compared, revealing that the reservoir tank induced low-frequency oscillations, which were absent in the closed-loop configuration. Additionally, experimental data were validated against theoretical noise models, showing reasonable agreement within mid-frequency ranges. As a foundational study, this research provides essential insights into the nature of pressure fluctuations caused by single-phase and two-phase flows and offers practical guidance for estimating their magnitudes in piping systems.