STR-849: FROM EXPERIMENTAL WIND TUNNEL TO WIND-STRUCTURE INTERACTION SIMULATIONS OF A SHELL STRUCTURE

This paper studies the transition from downscaled wind tunnel testing to prototype scale numerical simulations. The study is performed using OpenFOAM as fluid solver, EMPIRE as coupling tool, and Carat++ as the structure solver. The current work aims at finding sufficient settings for wind-structure interaction simulations. Also, the efficiency of the software chain to simulate natural wind flow is approved. For this purpose, different flow conditions such as uniform, atmospheric boundary layer (ABL), and flow behind a cube (structure is positioned in the wake region behind a cube) are simulated. These complicated, unsteady, and recirculating flows are simulated to study the aeroelastic effects on light weight shell structures. Wind-structure interaction simulations are performed where the dynamics of the structure play a crucial role in the wind effects. An Aluminum shell structure was tested in the wind tunnel to have an experimental benchmark for aeroelasticity. Throughout spectral analysis of structure vibrations and statistical evaluation of forces, the modeling approach shows a very good agreement with the experimental results. Finally, scaling issues represent a great challenge to wind tunnel testing especially when it comes to light-weight structures. While significantly, numerical simulations are shown to be an efficient tool for the prediction of wind loading on structure under different wind conditions

Particle-structure interaction using cad-based boundary descriptions and isogeometric B-REP analysis (IBRA)

The procedure and the properties with the use of NURBS-described CAD models in particle-structure interaction are presented within this contribution. This implies the needed entities of those models and the description of trimmed multipatches to discretize analysis suitable numerical models. Finally, the properties will be shown with some test cases in comparison to analytical benchmarks and simulations with FEM as boundary description

Multi-fidelity fluid–structure interaction analysis of a membrane blade concept in non-rotating, uniform flow condition

In order to study the aerodynamic performance of a semi-flexible membrane blade, fluid–structure interaction simulations have been performed for a non-rotating blade under steady inflow condition. The studied concept blade has a length of about 5 m. It consists of a rigid mast at the leading edge, ribs along the blade, tensioned edge cables at the trailing edge and membranes forming the upper and lower surface of the blade. Equilibrium shape of membrane structures in the absence of external loading depends on the location of the supports and the prestresses in the membranes and the supporting edge cables. Form-finding analysis is used to find the equilibrium shape. The exact form of a membrane structure for the service conditions depends on the internal forces and also on the external loads, which in turn depend on the actual shape. As a result, two-way coupled fluid–structure interaction (FSI) analysis is necessary to study this class of structures. The fluid problem has been modelled using two different approaches, which are the vortex panel method and the numerical solution of the Navier–Stokes equations. Nonlinear analysis of the structural problem is performed using the finite-element method. The goal of the current study is twofold: first, to make a comparison between the converged FSI results obtained from the two different methods to solve the fluid problem. This investigation is a prerequisite for the development of an efficient and accurate multi-fidelity simulation concept for different design stages of the flexible blade. The second goal is to study the aerodynamic performance of the membrane blade in terms of lift and drag coefficient as well as lift-to-drag ratio and to compare them with those of the equivalent conventional rigid blade. The blade configuration from the NASA-Ames Phase VI rotor is taken as the baseline rigid-blade configuration. The studied membrane blade shows a higher lift curve slope and higher lift-to-drag ratio compared with the rigid blade

Coupling the Discrete Element Method with the Finite Element Method to Simulate Rockfall Impact Experiments

To numerically simulate rockfall impact on flexible protection structures two different numerical methods are coupled within the open-source multi-physics code KRATOS. The impacting object is modeled with the help of a cluster of spherical discrete elements and its movement and contact forces are simulated using the Discrete Element Method (DEM). To realize a partitioned coupling simulation the contact forces are subsequently transferred to the light-weight protection structure which is analyzed and simulated using the Finite Element Method (FEM). To allow a stable simulation even in the case of large contact forces and/or large time steps a strong coupling GaussSeidel algorithm is presented. Subsequently the applicability of the method is shown by calculating experiments and finally the inclusion of digital terrain data is demonstrated