v2.02.119 SDLL119 - Beam bundle under axial fluid-elastic excitation

Summary

We consider a square-step bundle of \(3\times 3\) aluminum tubes, placed in a rectangular chamber and subjected to the action of an axial flow of water. The tubes contain lead pellets and are held together halfway up by piano strings. This hardware configuration corresponds to the experimental device of Hotta et al. [bib1] which is used to measure the changes in frequency and reduced damping of the first mode of flexure of the beam, as a function of the average speed of the flow.

The aim of this test case is to validate the resorption of the MEFISTEAU [R4.07.04] model making it possible to calculate the modal characteristics of a beam of beams under confined axial flow, taking into account fluid-elastic type excitation.

The features to be tested are as follows:

• operator DEFI_FLUI_STRU [U4.80.08]: definition of the parameters for taking into account fluid-elastic coupling, in the case of a configuration of the « bundle of tubes under axial flow » type (keyword factor FAISCEAU_AXIAL),

• operator CALC_FLUI_STRU [U4.80.03]: calculation of frequency changes and reduced modal damping as a function of the average flow speed, by implementing the MEFISTEAU model.

These functionalities should be tested with the complete representation of the beam and with a simplified representation.

The numerical results of the simulation of the device by Hotta et al. are validated by comparison with the experimental results. Given the relatively large uncertainties in the experimental values, the reference results for the non-regression of*Code_Aster* are those obtained numerically when the test case was returned.

• 1. Reference problem
  • 1.1. Geometry
  • 1.2. Material properties
  • 1.3. Boundary conditions and loads
  • 1.4. Bibliographical references
• 2. Benchmark solution
• 3. Modeling A
  • 3.1. Characteristics of modeling
  • 3.2. Characteristics of the mesh
  • 3.3. Calculation steps
  • 3.4. Tested values
  • 3.5. notes
• 4. B modeling
  • 4.1. Characteristics of modeling
  • 4.2. Characteristics of the mesh
  • 4.3. Calculation steps
  • 4.4. Tested values
• 5. notes