| This Thesis investigates theoretically and experimentally the dynamical behaviour and the stability of a cylindrical shell coaxially located in a rigid cylindrical pipe and subjected to internal or annular flow.; In the theoretical study, the shell could be clamped or pinned at both ends and the fluid flow in the inner shell and the annulus is assumed to be viscous and incompressible. The fluid forces consist of two parts: (i) steady viscous forces which determined using turbulent fully-developed theory; (ii) unsteady viscous forces which are derived by means of linearized Navier-Stokes equations. Shell motions are described by Flugge's modified shell equations. Two methods of solution are employed to formulate the problem. (1) Fourier transform techniques. (2) Travelling wave solutions.; The objectives are to investigate the effects of unsteady viscous forces as the dynamical behaviour and stability of the system in the presence and absence of steady forces.; Calculations have been conducted with a steel shell conveying water with different gap-to-radius ratios g/a{dollar}sb{lcub}rm i{rcub}{dollar} = 1/10 and 1-100.; First, the system is subjected to unsteady viscous forces only. It is found that, for internal flow and annular flow for g/a{dollar}sb{lcub}rm i{rcub}{dollar} = 1/10, the effects of viscosity on the stability of the system are insignificant; however, for the smaller gap (g/a{dollar}sb{lcub}rm i{rcub}{dollar} = 1/100), those effects are more pronounced, rendering the system more stable. When both steady and unsteady viscous forces are applied, the results are quite different from the previous case. For internal flow, the system becomes more annular flow, the system loses stability at much lower velocities for both gap-systems.; In the experimental study, the flow is only annular. The shell could be clamped at both ends or clamped at one end and free at the other. For the clamped-clamped shell, the system loses stability by divergence (buckling) as predicted by linear theory. However, coupled-mode flutter was never observed experimentally. Clamped-free shells, on the other hand, lose stability by flutter. |
