Three-Dimensional Finite Element Analysis of Aerodynamic Forces Acting on an Oscillating Subsonic Linear Cascade. 2nd Report. Effects of Dihedral Angle, Sweep Angle and Taper Ratio.

Abstract

In the present paper, the three-dimensional finite element method developed to calculate the aerodynamic forces acting on the vibrating cascade blades in a subsonic flow is applied to various flow conditions and geometrical configurations. The present FEM formulation using pentahedra instead of tetrahedra reproduces perfectly two-dimensional solutions when applied to the spanwise uniform model. Calculations have been made for three-dimensional configurations with various dihedral angles, sweep angles and taper ratios. In most cases, three-dimensional effects due to taper on steady and unsteady aerodynamic forces appear as the effects of decreasing spanwise variation of steady and unsteady forces, respectively, when the angle of attack is uniform along the span. Three-dimensional effect due to taper becomes small when the angle of attack is nonuniform along the span. The effect of dihedral is small compared with the effect of sweep or taper. The effect of sweep on unsteady aerodynamic forces becomes extremely conspicuous when the steady loading is nonuniform along the span.