51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013
JAN 07-10, 2013
Grapevine, TX, United states
The limitations of the Kutta-Joukowski (K-J) theorem in prediction of the time-averaged and instantaneous lift of an airfoil and a wing in low-Reynolds-number unsteady flows are examined. A general lift formula for a rectangular control volume is given in a very simple form in the framework of viscous flow theory, which provides a rational foundation for a direct comparison with the K-J theorem considered as a reduced case. Direct numerical simulations on the stationary and flapping flat plate and rectangular wing are conducted to assess the accuracy of both the K-J theorem and the general lift formula. In particular, the Lamb vector integral for the vortex force and the acceleration term of fluid for the unsteady inertial effect are evaluated as the main contributions to the unsteady lift generation of a flapping wing.
American Institute for Aeronautics and Astronautics (AIAA)
Wang SZ,Zhang X,He GW,et al. On applicability of the Kutta-Joukowski theorem to low-Reynolds-number unsteady flows[C]51st AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition 2013,2013:AIAA 2013-0067.