Kite Flight Simulators Based on Minimal Coordinate Formulations

Abstract

Analytical mechanics techniques are applied to the construction of three kite flight simulators with applications to airborne wind energy generation and sport uses. All of themwere developed under a minimal coordinate formulation approach. This choice has the main advantage of yielding a set of ordinary differential equations free of algebraic constraints, a feature that distinguishes the simulators from codes based on classical mechanics formulation and improves their robustness and efficiency. The first simulator involves a kite with a flexible tether, a bridle of variable geometry, and several on-board wind turbines. Such a simulator, which models the tether by a set of rigid bars linked with ideal joints, can be used to study the on-ground generation of electrical energy through yo-yo pumping maneuvers and also the onboard generation by the wind turbines. The second simulator models a kite linked to the ground by two rigid control lines. This numerical tool is aimed at the study of the dynamics of acrobatic kites and the traction analysis of giant kites to propel cargo ships. The third and last simulator of this work considers a kite with four control lines similar to the ones used in kitesurf applications. Two of them are rigid tethers of constant length that connect the leading edge of the kite with a fixed point at the ground. The other two tethers are elastic and they link a control bar with the trailing edge of the kite. The performances of the simulators in terms of computational cost and parallelization efficiency are discussed. Their architectures and user interfaces are similar, and appropriate to carry out trade-off and optimization analyses for airborne wind energy generation.