Dynamics and stability of pinned-clamped coaxial cylindrical shells conveying viscous flow

This thesis presents a theoretical study of the stability of pinned-clamped and clamped-pinned coaxial cylindrical shells conveying internal and/or annular incompressible viscous fluid flow.;In the present analytical model, fluid viscous effects are taken into consideration. Generally, the viscous nature of the fluid results in both steady and unsteady viscosity-related loads being exerted on the shells, the latter of which are approximated by their inviscid counterpart in this thesis. Upstream pressurization of the flow (to overcome frictional pressure drop) and skin friction on the shell surfaces are taken into account, generating time-averaged normal and tangential loads on the shells. In this model, the shell motions are described by Flugge's shell equations, suitably modified to incorporate the time-averaged stress resultants arising from viscous effects. The unsteady fluid-dynamic forces in these equations are formulated from potential flow theory: the perturbation pressures on the shells are determined from the perturbation velocity potentials via the unsteady Bernoulli equation; those velocity potentials are governed by the Laplace equation, which is solved by the Fourier transform technique.;For the clamped-pinned system, since the downstream end of the shell is simply supported, a so-called out-flow model is utilized in modelling the decay of flow perturbations beyond the pinned end.;Comparison is made with the existing results for clamped-clamped and clamped-free cases.;Finally, future work is suggested with regard to setting up a new analytical model with the unsteady viscous effects taken into account.