47 Roland Schmehl Delft University of Technology Faculty of Aerospace Engineering Wind Energy Section Kite Power Research Group Kluyverweg 1 2629 HS Delft The Netherlands r.schmehl@tudelft.nl http://www.kitepower.eu
Flight Dynamic Modelling of Inflatable Membrane Kites
including Aeroelasticity Effects
Roland Schmehl1, Paolo Tiso2
1Faculty of Aerospace Engineering, Delft University of Technology
2Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology
The flexibility of kites and tethers is a challenge for modeling and simulation of many Airborne Wind Energy Systems. This holds particularly for the lightweight membrane structure of an inflatable kite under aerodynamic loading. The structural dynamics and exterior aerodynamics are strongly coupled and dominate the flight dynamic characteristics, the steering and de-powering of the wing. The presentation describes a nu-merical modeling approach for the flight dynamics of a teth-ered inflatable wing as a central component of a kite pow-er system. The deformation of the wing is described within a geometrically nonlinear Finite Element framework to cov-er large displacements that occur due to changing bridle line geometry and varying aerodynamic loading. The effect of the external flow is described in terms of discrete pressure distri-butions for the different wing sections. The empirical model
takes into account the shape parameters chord length, cam-ber and thickness per section and is derived by fitting pre-computed data from Computational Fluid Dynamic analysis. To reduce computation times, local dynamic deformation phenomena are neglected. Each integration time step, the steady aerodynamic loading is determined first and subse-quently used to update the static equilibrium shape of the wing. This static aeroelastic model is embedded in a dynam-ic system model whdynam-ich includes all remaining airborne com-ponents tether, bridle lines and Kite Control Unit. The itera-tive approach can accurately describe bending and torsion of the wing, which contribute to the aerodynamic steering mo-ments. The presented approach is used to simulate figure-eight flight maneuvers which are typical for Airborne Wind Energy systems. Ph ot o: C hr is S la pp en de l
