An Arnoldi approach for generation of reduced-order models for turbomachinery

A linear reduced-order aerodynamic model is developed for aeroelastic analy sis of turbomachines. The basis vectors are constructed using a block Arnol di method. Although the model is cast in the time domain in state-space for m, the spatial periodicity of the problem is exploited in the frequency dom ain to obtain these vectors efficiently. The frequency domain proper orthog onal decomposition is identified as a special case of the Arnoldi method. W e show an application where the aerodynamic model is coupled with a simple structural model that has two degrees of freedom for each blade. The techni que is applicable to viscous and three-dimensional problems as well as mult i-stage problems with inlet and exit disturbance flows, although here resul ts are presented for two-dimensional, inviscid flow through a 20-blade sing le-stage rotor. In this case, the number of states of the model is on the o rder of 10 per blade passage, making it appropriate for control application s. (C) 2001 Elsevier Science Ltd. All rights reserved.