Excitation Force Identification of Rotating Machines Using Operational Rotor/Stator Amplitude Data and Analytical Synthesized Transfer Functions

Hydraulic excitation forces of rotating machinery are normally determined by direct measurement techniques like strain gages, load cells, etc. This paper presents an indirect method, in which frequency response transfer functions are analytically generated, using linear rotor/stator models. Inverse transfer function matrices are multiplied with operational vibration data to yield fourier transformed operational excitation forces. Analytical excitation techniques and numerical inversion methods of the system transfer function matrix are evaluated. External error sources and guidelines for an error sensitivity analysis of the predicted forces are described. Experimental verification is presented on a large horizontal centrifugal pump, with reasonable results. Typical application is shown on multistage hydro carbon and boilerfeed pumps.