Analyse des Schlagfluges mit verformten Flügeln

Abstract The present thesis covers the design of a birdlike aerofoil and three-dimensional wing. The ob- jecitve of this work is to transfer two-dimensional aerofoil kinematics to this three-dimensional wing retaining values of thrust and propulsive efficiency and to give a prospect of the efficiency of realistic and natural wing kinematics. Furthermore the effect of variying wing motion on the generation of thrust and propulsive efficiency is studied using computational fluid dynamics and grid deforming technique. Therefore well analysed two-dimensional airfoil kinematics are extended to three-dimensional flapping wings. Three-dimensional effects decrease the effective angle of attack and result in re- duced values of thrust and propulsive efficiency. The induced angles of attack on finite wings are identified with a stationary vortex system method and taken into to account by defining the wing flapping motion. The results in thrust and propulsive efficiency of the wing’s design section of moderate motion deflection cases with high propulsive efficiency show good agreement compared with equivalent two-dimensional values. For cases with larger amount of deflections the three-dimensional simulation did come close to the two-dimensional results. This is due to large tip vortices and a flow separation on the pressure side during upstroke. Analysis of wing motion with large deviations demonstrate limitations of the stationary vortex system to identify the induced angles of attack. This limits illustrate the need to consider un- steady effects into the identification of induced angles of attack using non-linear methods with high order polynomials. The results of this work demonstrate the flapping motion’s sensitivity to parameter changes.