Articulated pipes conveying fluid pulsating with high frequency
The author investigates stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component. The non-autonomous model equations are converted into autonomous ones by approximating fast excitation terms with slowly varying terms. The downward hanging pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe masses, and to marginally destabilize this position for low ratios. The author presents stability analysis of the downward hanging position with respect to flutter instability, showing the stabilizing/destabilizing effects of the high-frequency flow pulsations. The method of multiple scales is used to analyse local nonlinear behaviour, i.e. the transition from super- to sub-critical Hopf bifurcations when the pulsating fluid component is added. Then the large-amplitude flutter motion is analyzed by using a path-following program based on numerical integration of the autonomous set of model equations.
scientific article; zbMATH DE number 1396391