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

Pressure fluctuations caused by multiphase flow in piping systems can lead to structural vibration, noise generation, and potential damage to the piping infrastructure. This study examined flow-induced pressure fluctuations and their spatial distribution on the pipe walls for single-phase and two-phase flows in a horizontal straight pipe. The experiments were conducted using a flow test loop under various flow velocities and water fractions. A simplified one-dimensional numerical model was used to examine the influence of a reservoir tank on the pressure magnitude and distribution within the piping system. The results showed that pressure fluctuations in single-phase flow are governed primarily by the flow velocity, whereas those in two-phase flow are strongly influenced by water fraction and free-surface deformation. Comparisons between open-loop and closed-loop conditions showed that the reservoir tank induces low-frequency oscillations that disappear in the closed-loop configuration. These findings provide fundamental experimental data for understanding flow-induced pressure fluctuations and their implications for vibration and noise in piping systems used in marine and offshore engineering applications.