Direct Calculation of Three-Dimensional Indicial Lift Response Using Computational Fluid Dynamics

Abstract

An unsteady Euler solver is modie ed to calculate the indicial response of a rectangular wing to a step change in the angle of attack. In this new approach the grid time metrics include the velocity caused by the impulsive change in angle of attack, but the mesh is not moved accordingly. This approach avoids numerical instabilities and decouples the step change in the angle of attack from a pitch rate. Numerical results are validated by comparison with analytical results for two-dimensional indicial responses. The application of the same method to rectangular wings reveals important characteristics of the three-dimensional indicial response. It is found that the direct calculation of the indicial response using computational e uid dynamics gives quite accurate results and provides a rich database, in the absence of experimental data, to validate the approximations to indicial response.