Unsteady Transonic Aerodynamics in Frequency Domain and Calculation of Flutter Characteristics of Aircraft

This paper describes a finite-difference method for unsteady transonic flow computation in frequency domain and transonic flutter prediction of complete aircraft configurations. The unsteady TSD equation as well as the boundary conditions are split into the in-phase and out-of-phase components in frequency domain by a nonlinear harmonic averaging technique. The resulting equations are solved by a steady flow algorithm.

The unsteady pressure distributions for a rectangular wing and the ONERA M6 wing are analyzed and compared with other results to verify the code.

The flutter characteristics for the AGARD I-445.6 wing, a cropped delta wing and a fighter configuration are computed and the results are discussed.