Calculation of Vibration Characteristics of Water Transport Elbow based on Fluid-structure Interaction

Abstract

The fluid-structure interaction (FSI) in transportation pipelines directly affects the characteristics of the pipe, primarily causing pipeline vibration. The FSI computational model of a water transport elbow impacted by the fluctuating pressure was established, considering the pressure amplitude and frequency of pulsating fluids, as well as the wall thickness to diameter ratio. Force and modal analyses were conducted using ANSYS Workbench software. Results show that the maximum deformation occurs in the middle of the bending section. The natural frequency of the elbow is significantly reduced under FSI, with the sixth natural frequency reduced by 35.9% to 610.48 Hz. As the excitation frequency increases, the displacement and acceleration response of the monitoring point exhibit peaks at the second and fifth natural frequencies, respectively. To minimize the impact of resonance on the lifespan of pipelines, elbows with large bending-to-diameter ratio should be used for low-frequency vibration conditions, whereas bent pipes with small bending-to-diameter ratio should be used for high-frequency vibration conditions. This approach simultaneously increases the wall thickness at the pipeline connections.