A fluid-multibody coupling for aeroelastic applications to rotorcraft and wind turbines

Abstract

Accurate aerodynamic and aeroacoustic simulations of helicopters and wind turbines require the inclusion of the blade elasticity into the computational setup. If low-order aerodynamic models can be efficient for optimization purposes, they are often insufficient in predicting the complex flow phenomena responsible for structural vibrations and noise. For this purpose, high-fidelity Computational Fluid Dynamics solvers coupled with Multi-Body Dynamic tools can be exploited for more accurate simulations in the context of detailed design.

This thesis focuses on the development of a coupling methodology between the Lattice-Boltzmann flow solver PowerFLOW and the Multi-Body Dynamic tool Simpack for pitching and plunging airfoils featuring lumped structural parameters. This is achieved by verifying the fluid and multibody simulation setups separately against theoretical models. Then, the coupling is compared against analytical aeroelastic solutions for several amplitudes and reduced frequencies of motion. In addition, different approaches to model the airfoil motion in the fluid solver are assessed and compared favorably against each other. As a conclusive effort, the coupling is applied to a bi-dimensional airfoil flutter case returning a prediction of the flutter velocity within a 1% difference with respect to analytical methods.