The Calculation And Verification Of Torsional Natural Frequencies For Turbomachinery Equipment Strings

Abstract

The analytical techniques used to design turbomachinery equipment strings from a torsional dynamics standpoint are discussed. Consideration is also given to both torsional natural frequency placement and potential excitation sources. Three cases are presented wherein the torsional natural frequencies and mode shapes are calculated via Holzer Transfer Matrix computer code and the frequencies then verified by measurement on the actual hardware. The accuracy of both analytical and measuring techniques is discussed from the aspect of the minimum acceptable interference margins for acceptable equipment operation.