Dynamic modelling of a flexible kite for power generation

Dynamic modelling of a flexible kite for power generation: Coupling a fluid-structure solver to a dynamic particle system

Geschiere, N.H.

van Bussel, G.J.W. (mentor)
Schmehl, R. (mentor)
Tiso, P. (mentor)

Aerospace Engineering

Wind Energy

2014-05-01

This thesis investigates the dynamic modelling of a kite power system. The goal was to create a model that is able to capture the complex flight dynamic behaviour of a kite. A proof-of-concept already existed. From that work the steady fluid-structure interaction (FSI) module, using finite elements (FE), was used and coupled to a bridle and tether model. The bridle and tether model is based on an existing tether model that used spring-dampers. The tether model was then extended to include the full bridle system and steering due to line deflection. The focus thus lies in their coupling. An interface was created to couple the two models, such that the dynamic bridle model calls the FSI model at the end of every time step. For stability reasons the ends of the bridles were included in the FE model, so that high forces perpendicular to the bridle lines are avoided. In addition, spring-dampers with a low stiffness but high damping were placed between the bridle boundary points. Yet, due to a lack of aerodynamic damping in the FSI module, the kite proved to be unstable. Therefore artificial damping was implemented, based on the differential between the bridle particles' individual velocity and the wing's overall velocity. This resulted in a model capable of simulating the dynamic flight behaviour of a kite power system. This was compared to the empirical turn rate law, which was tuned to KitePower's technology demonstrator. It was found that the turn rate of the simulation matched qualitatively, but not quantitatively, due to the inevitable need for artificial damping.

Windenergy

http://resolver.tudelft.nl/uuid:6478003a-3c77-40ce-862e-24579dcd1eab

Student theses

master thesis

(c) 2014 N.H. Geschiere