Fluid–structure interaction characteristics and mechanisms of full-flow pattern boiling two-phase flow in uniform curvature inclined tube

This study combines experiments and theoretical analysis to investigate the fluid–structure interaction of boiling two-phase flow in uniform curvature inclined tube. The research aims to clarify the vibration response characteristics induced by full-flow pattern boiling two-phase flow, elucidate the intrinsic relationship between thermohydraulic parameters and vibration responses, and uncover the underlying interaction mechanisms. The results indicate a clear spatial distribution in the vibration response caused by full-flow pattern boiling two-phase flow, which strongly correlates with the distribution of two-phase flow patterns in the tube. Sensitivity analysis of thermal–hydraulic parameters indicates that changes in inlet mass flow rate and system pressure affect both vibration displacement and frequency, while variations in inlet subcooling primarily influence vibration frequency. Additionally, the experimental results reveal that vibration displacement initially increases and then decreases with increasing void fraction. The significant influence of void fraction on both the magnitude and frequency of vibration is demonstrated, and a new dimensionless number is proposed to better quantify the impact of thermal–hydraulic parameters on vibration responses. Furthermore, by analyzing the two-phase flow patterns, the study elucidates the intrinsic connections between factors such as centrifugal force, secondary flow, and interfacial friction and the resulting vibration responses. The mechanisms of fluid–structure interaction associated with annular flow, bubbly flow, and slug flow are revealed, and a far-field excitation mechanism driven by pressure wave propagation is identified.