Dynamics of inclined cantilevered piping system conveying slug flow

This paper investigates the dynamics of an inclined cantilevered pipe subjected to slug flow using experimental and theoretical approaches. The model equation is simplified using the equivalent flow parameter, followed by discretization via the Galerkin truncation technique. Frequency-domain experimental methods were employed to provide a more direct and scientific basis for understanding the natural frequency fluctuations in slug flow systems while also validating the accuracy of the equivalent flow parameters proposed earlier. Experimental findings revealed that the system's natural frequency exhibits fluctuation characteristics, with the amplitude of these fluctuations dependent on the inclination angle and the superficial gas velocity. Furthermore, profound insights are provided into the predominant added mass effects observed in the system. Linear analysis showed that the type of system instability, whether buckling or flutter, is influenced by gas velocity and the inclination angle. Superficial gas velocity is critical in transitioning the system's instability mechanism from buckling at a lower value to flutter at a higher value. Nonlinear analysis highlighted a shift in instability mechanisms, moving from buckling to a stable state and then to flutter. Finally, the transition to chaotic behavior was primarily governed by period-doubling bifurcations.