A Study on Unsteady Aerodynamic Characteristics of Oscillating Cascades with Arbitrary Blade Profiles : Two-Dimensional Cascades Oscillating with Blade Section Deformation

Abstract

Aerodynamic characteristics of oscillating cascades of blades accompanied by elastic deformation of blade sections in a uniform incompressible flow are predicted numerically. Unsteady formulation is based on a small perturbation approach with the use of potential equations expressed on a moving computational grid. The governing equations are discretized by the finite element method. Modal shapes of blade oscillation are obtained first and a parametric study on unsteady aerodynamic characteristics is conducted for the two-dimensional cascade of the tip section of a test compressor. Furthermore, the oscillation displacement of the blades is divided into four components, i.e., two translational components (normal and tangential to the blade chord), a rotational component, and a section-deformation component, in order to analyze the contribution of each component to unsteady aerodynamic work which causes flutter excitation. It is shown that the effect of the blade section deformation is very significant in determining the unsteady characteristics of oscillating cascades.