Estimation of Forcing Function for a Geometrically Mistuned Bladed Rotor Via Modified Modal Domain Analysis

Abstract

Modified modal domain analysis (MMDA) is a method to generate an accurate reducedorder model (ROM) of a bladed disk with geometric mistuning. An algorithm based on the MMDA ROM and a state observer is developed to estimate forcing functions for synchronous (including integer multiples) conditions from the dynamic responses obtained at few nodal locations of blades. The method is tested on a simple springmass model, finite element model (FEM) of a geometrically mistuned academic rotor, and FEM of a bladed rotor of an industrialscale transonic research compressor. The accuracy of the forcing function estimation algorithm is examined by varying the order of ROM and the number of vibration output signals.