Abstract
The design of bladed disks involves both fluid dynamic and structural calculations through numerical methods that involve the discretization of the domains. On the fluid side, computational fluid dynamics (CFD) software is used while on the structural side, models are formulated by the finite element (FE) method and are reduced using different model reduction techniques.
The fluid and the structural model are coupled as the aerodynamic pressure induces a load on the blades, while the blade deformation changes the boundary conditions for the flow field. In industrial applications, this fluid-structure interaction problem is usually implemented only partially, adopting a oneway coupling.
In forced-response calculation, the aerodynamic pressure is calculated using the geometry obtained, including the static blade deformation (mean pressure load, centrifugal force, temperature), disregarding the dynamic part of the response. The dynamic pressure field calculated in this way is then used as a dynamic load for the structural model. On the other hand, in flutter analyses, the blade motion is prescribed according to a selected mode shape, frequency and inter-blade phase angle and is used to define the boundary conditions for the CFD model. In both situations, it is necessary to transfer information (pressures or displacements) between the fluid and the structural model.
This paper describes a technique to transfer the pressure field calculated by a CFD analysis to a structural Reduced-Order Model (ROM) obtained from a high-fidelity FE model of the disk. The generalized forces acting on the ROM are obtained as a linear mapping of the pressure computed on the boundary of the CFD domain. This mapping depends only on geometry and mesh topologies, thus it can be calculated only once in a structural analysis, while for each time or frequency step, the generalized forces are obtained through a matrix multiplication.
