v8.01.106 FDLV106 - Calculation of damping added in annular flow

Summary:

This fluid/structure test involves calculating the mass and damping added to a cylindrical structure subjected to an annular flow that is assumed to be potential. Initially, mass and damping added by the flow on the structure are calculated for various upstream speeds (\(4m/s\), \(4.24m/s\) and \(6m/s\)), on a 3D model for the fluid and shell for the structure. The structure has a rotational movement around a pivot located at the downstream end of the cylinder with respect to the flow.

The coefficients determined are assigned to a discrete model equivalent to 1 ddl mass-spring-damper, on which a modal analysis is carried out, in order to determine the complex natural frequencies of the system for the various flow velocities:

\(4m/s\): amortization,

\(4.24m/s\): critical speed, zero damping,

\(6m/s\): negative damping, floating.

• 1. Reference problem
  • 1.1. Geometry
  • 1.2. Material properties
  • 1.3. Boundary conditions and loads
• 2. Benchmark solution
  • 2.1. Calculation method used for the reference solution
  • 2.2. Benchmark results
  • 2.3. Bibliographical references
• 3. Modeling A
  • 3.1. Characteristics of modeling
  • 3.2. Tested values
• 4. Summary of results