A LINEARIZED UNSTEADY MODEL FOR COMPUTING DYNAMICS OF CYLINDRICAL STRUCTURES SUBJECTED TO NONUNIFORM ANNULAR FLOWS AT HIGH REYNOLDS NUMBERS

Abstract The stability of co-axial cylindrical structures subjected to annular flows has received a lot of attention in the last few years. Configurations of this kind are widely encountered in Pressurized Water Reactor (PWR) components and are therefore of important practical interest. This paper presents a linearized unsteady model for computing the fluid–structure interaction between an axial annular flow and a vibrating structure. This model, implemented into a computer code, MOCCA, deals with an incompressible viscous fluid, flowing at high Reynolds number, in a finite length annular region the cross-section of which may vary continuously with axial position. Both differences and similarities with the model previously developed by Hobson are pointed out. A comparison is also made with experimental data, for a cylinder that is free to oscillate under the action of a nonuniform annular flow.