The Connection between flow pattern evolution and vibration in 90-degree pipeline: Bidirectional fluid-structure interaction

Fluid-structure coupling is the main cause for the vibration of fluid-conveying pipelines, and fluid-solid coupling vibration of fluid-conveying pipelines is a "typical dynamic problem." The present paper analyzes the dynamic characteristics and dynamic response of the elbow with simultaneous dual-thread analysis, aiming to clarify the dynamic change law of pipe vibration induced by gas-liquid two-phase flow in the elbow. It can be concluded that the characteristics of the slug flow developed from the interphase instability mechanism have been captured in the volume of fluid (VOF) method. The dynamic evolution information of different two-phase flow patterns is often accompanied by complex self-similarity, but has different complex structures, chaotic characteristics, and dynamic behaviors. The unique modal frequencies of each order are applied to the elbow to obtain different exclusive mode shapes. The evolution of the flow pattern is related to the increase in the wave height, and the wave amplitude often depends on the gas-liquid superficial velocity. The superficial liquid velocity is more sensitive to the influence of flow pattern formation and vibration than that of gas.