Forced response analysis of aerodynamically asymmetric cascades
The effect of aerodynamic asymmetries on forced response characteristics of cascades is investigated. Specifically, the present method is used to study the effect of leading edge blending in loaded rotors. The unsteady aerodynamic response of the blades to self-excited vibrations and gust response is modeled using a harmonic balance method, which allows one to model the entire wheel using complex periodic boundary conditions and a computational grid spanning a single sector (symmetry group). This reduces the computational and memory requirements dramatically compared to similar time-accurate analyses. The results show that compared to symmetric cascades, the amplitude of the forcing functions due to wake passing see an increase for blended rotors. The maximum amplification factors for forced response calculations are found to be around 1.3, which are significantly lower than the case of typical frequency mistuning. This indicates that there is no mode localization effect due to aerodynamic asymmetries. Copyright © 2010 by Kivanc Ekici, Robert E. Kielb and Kenneth C. Hall.
