DIRECT CALCULATION OF 3-DIMENSIONAL INDICIAL LIFT RESPONSE USING COMPUTATIONAL FLUID-DYNAMICS

An unsteady Euler solver is modified to calculate the indicial respons e of a rectangular wing to a step change in the angle of attack. In th is new approach the grid time metrics include the velocity caused by t he impulsive change in angle of attack, but the mesh is not moved acco rdingly This approach avoids numerical instabilities and decouples the step change in the angle of attack from a pitch rate, Numerical resul ts are validated by comparison with analytical results for two-dimensi onal indicial responses. The application of the same method to rectang ular wings reveals important characteristics of the three-dimensional indicial response, It is found that the direct calculation of the indi cial response using computational fluid dynamics gives quite accurate results and provides a rich database, in the absence of experimental d ata, to validate the approximations to indicial response.