Dynamics of two coaxial cylindrical shells containing viscous fluid

Technical Report · Wed Sep 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7249428· OSTI ID:7249428

Yeh, T T; Chen, S S

This study was motivated by the need to design the thermal shield in reactor internals and other system components to avoid detrimental flow-induced vibrations. The system component is modeled as two coaxial shells separated by a viscous fluid. In the analysis, Flugge's shell equations of motion and linearized Navier-Stokes equation for viscous fluid are employed. First, a traveling-wave type solution is taken for shells and fluid. Then, from the interface conditions between the shells and fluid, the solution for the fluid medium is expressed in terms of shell displacements. Finally, using the shell equations of motion gives the frequency equation, from which the natural frequency, mode shape, and modal damping ratio of coupled modes can be calculated. The analytical results show a fairly good qualitative agreement with the published experimental data. Some important conclusions are as follows: (1) In computing the natural frequencies and mode shapes of uncoupled modes and coupled modes, the fluid may be considered inviscid and incompressible. (2) There exists out-of-phase and in-phase modes. The lowest natural frequency is always associated with the out-of-phase mode. (3) The lowest natural frequency of coupled modes is lower than the uncoupled modes. (4) The fluid viscosity contributes significantly to damping, in particular, the modal damping of the out-of-phase modes isrelatively large for small gaps. (5) If the fluid gap is small, or the fluid viscosity is relatively high, the simulation of the vibration Reynolds number should be included to ensure that modal damping of the model is properly accounted for. With the presented analysis and results, the frequency and damping characteristics can be analyzed and design parameters can be related to frequency and damping.

• Research Organization: Argonne National Lab., Ill. (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 7249428
• Report Number(s): ANL-CT-76-48
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100* -- Nuclear Reactor Technology-- Theory & Calculation
CONFIGURATION
CYLINDRICAL CONFIGURATION
FLUID FLOW
MATHEMATICAL MODELS
MECHANICAL VIBRATIONS
REACTOR COMPONENTS
REACTOR INTERNALS
SHELLS
VISCOUS FLOW