Unsteady Aerodynamic Forces Acting on Vibrating Cascade Blades in a Three-Dimensional Flow Field

抄録

A method was developed for calculating unsteady aerodynamic forces acting on vibrating cascade blades in a three-dimensional flow field. Blades were allowed to have nonuniform span-wise steady loading, and to be vibrating in three-dimensional modes. The effects of wake deformation behind blade trailing edges were also considered. It was shown that nonuniform steady loading along the span controlled the unsteady aerodynamic characteristics of vibrating blades at lower reduced frequencies, and the effects of wake deformation became relatively significant at higher reduced frequencies. Compared to the results by a two-dimensional strip theory, there were considerable differences at lower reduced frequencies, especially in the case of highly loaded and staggered cascades. A high-order vibrating mode was also investigated in which an airfoil section might change its chord-wise shape significantly. The results indicated that this mode could be critical in determining the flutter boundary.