A mesh morphing based FSI method used in aeronautical optimization applications

In this paper a fast and efficient mesh morphing based technique to perform FSI analyses for aeroelastic design and optimization applications is presented. The procedure is based on the finite volume CFD solver (OpenFOAM® and SU2) coupled with the RBF Morph™ tool capable of deforming the surface and volume mesh of the computational domain according to the mode superposition method. Structural vibration modes of the geometry of interest are calculated in a pre-processing stage by means of a FEM solver and later imported into the RBF Morph™ tool to create a set of individual basic deformations. Aerodynamic loads calculated with a CFD solver are then projected onto the accounted structural modes to get modal loads and modal coordinates which are applied to the computational model in order to obtain the deformed configuration. An FSI cycle incorporating a CFD simulation and morphing of its mesh can be iteratively repeated upon convergence to the final deformed shape. Since the modal parameterization and the mesh calculation have to be prepared only once per FSI analysis, its computation time is drastically reduced compared to a standard two-way coupling method in which a structural analysis has to be done at each cycle. Present procedure was applied to two geometries, HIRENASD fuselage-wing geometry for the purpose of testing the procedure and a Pipistrel's electric aircraft propeller for the purpose of optimization of its shape. By utilizing a DoE and a response surface method an increase of four percent of propeller efficiency was obtained by converging to a most favourable propeller pitch and twist configuration incorporating also FSI deformation. The above-mentioned procedure was developed in the framework of the EU-funded RBF4AERO project.

In this paper a fast and efficient mesh morphing based technique to perform FSI analyses for aeroelastic design and optimization applications is presented. The procedure is based on the finite volume CFD solver (OpenFOAM® and SU2) coupled with the RBF Morph" tool capable of deforming the surface and volume mesh of the computational domain according to the mode superposition method. Structural vibration modes of the geometry of interest are calculated in a pre-processing stage by means of a FEM solver and later imported into the RBF Morph™ tool to create a set of individual basic deformations. Aerodynamic loads calculated with a CFD solver are then projected onto the accounted structural modes to get modal loads and modal coordinates which are applied to the computational model in order to obtain the deformed configuration. An FSI cycle incorporating a CFD simulation and morphing of its mesh can be iteratively repeated upon convergence to the final deformed shape. Since the modal parameterization and the mesh calculation have to be prepared only once per FSI analysis, its computation time is drastically reduced compared to a standard two-way coupling method in which a structural analysis has to be done at each cycle. Present procedure was applied to two geometries, HIRENASD fuselage-wing geometry for the purpose of testing the procedure and a Pipistrel's electric aircraft propeller for the purpose of optimization of its shape. By utilizing a DoE and a response surface method an increase of four percent of propeller efficiency was obtained by converging to a most favourable propeller pitch and twist configuration incorporating also FSI deformation. The abovementioned procedure was developed in the framework of the EU-funded RBF4AERO project (Grant Agreement No: 605396) and is available through the RBF4AERO platform.