Transverse free vibration and stability analysis of spinning pipes conveying fluid

In this paper, the transverse free vibration and stability are analyzed for spinning pipes conveying fluid as a typical example of doubly gyroscopic systems. The partial differential equations of motion are derived by the extended Hamilton principle, and are then truncated by the 4-term Galerkin technique. The natural frequencies, complex modal motions and responses to initial conditions are comprehensively investigated to display the essential dynamical properties of such spinning structures conveying fluid. It is indicated that the qualitative stability of the present system mainly depends on the effects of fluid-structure interaction (FSI) and mass ratio, while the spinning speed plays a significant role in determining the quantitative values of the frequency. The critical flow velocities are independent of the spinning speed and mass ratio. Forward and backward whirling motions are found to take place alternatively for the first four modes, and a 'traveling wave' with spatial configuration is observed during vibrations. The gyroscopic couplings caused by spin and FSI will yield great impacts on the energy transfers between different general coordinates. (C) 2018 Elsevier Ltd. All rights reserved.