Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
A Unified Approach for the Dynamics of Flexible Tethered Wings
Submission Author:
Olaf Palmer Val Pinheiro , SP
Co-Authors:
Olaf Palmer Val Pinheiro, Flavio Luiz Cardoso-Ribeiro, Mauricio Andrés Varela Morales
Presenter: Olaf Palmer Val Pinheiro
doi://10.26678/ABCM.COBEM2021.COB2021-0833
Abstract
The Airborne Wind Energy (AWE) is a growing field of research that intends to develop solutions for harvesting wind energy using airborne vehicles. The main advantage of this concept is the capability to explore high altitude winds, which are typically stronger and less variable than in low altitudes. In addition, airborne vehicles tend to require only a fraction of infrastructure costs, when compared with the traditional wind turbines. One usual AWE design is the Leading Edge Inflatable (LEI) kites. In the current Airborne Wind Energy (AWE) literature, many modeling strategies for the dynamics of tethered wings are proposed. Important works explored the typical ground generation AWE system with flexible LEI wings, adopting a variety of combinations of wing structural, aerodynamic and tether models. Notably, flexible LEI wings have already been modeled using membrane and inflatable beam elements. The time-integration scheme included a static structural solution at each time step and simplified aerodynamic and tether models. On the other hand, the studies on flexible aircraft dynamics have been a well established subject of research. A useful idea in modeling flexible aircraft is adding the equations of the elastic degrees of freedom (DOFs) using modal coordinates. Aerodynamic forces can be provided by low fidelity methods. As LEI wings are usually very flexible structures, it emerges an opportunity to apply this same methodology to the AWE systems. Additionally, the tether dynamics can be included, taking into account the effects of flexibility, weight distribution and drag forces over the tether. This work will present an approach that unifies: 1) Flight dynamics, with the classical rigid-body 6 DOFs; 2) Structural dynamics, with wing elastic DOFs in modal coordinates; 3) Tether dynamics, including the DOFs of the flexible tether, as well as the control inputs in the bridle lines; and 4) Quasi-steady aerodynamics, using a Vortex Lattice Method (VLM) implementation, resulting in a seamless integration framework. Therefore, this work intends to bring to AWE an application of an established knowledge in the flexible aircraft dynamics, in order to provide a suitable methodology for the dynamics of a flexible tethered wing. A generic LEI kite design is studied. The mode shapes and frequencies are obtained via Finite Element Method (FEM)."
Keywords
Airborne Wind Energy, Flight dynamics, Tethered Wings, flexible aircraft dynamics
