Thermodynamical and mechanical modelling analysis of high-speed turbomachine rotors

Authors

E. Saari, J. Backman, J. Larjola - Lappeenranta University of Technology, Finland

Abstract

In this study it is considered problems appearing in the different applications of high-speed technology, having as the viewpoint the rotor structure. High-speed technology means a system, where the electric machine and the unit to be driven (turbine, compressor) are directly coupled to each other without a gear box, and where the speed of this common shaft is significantly higher than the synchronous speed of two pole electric machines connected to the 50/60 Hz network. The high power density is typical for rotors of high-speed machines. The objective of this study is to analyze the mechanical structure of the combined electric machine – turbo machine rotor in three points of view: 1) the literature review and summary of governing equations for design of high speed machines. 2) to reduce the heat sources and to improve the cooling of critical points. This involves the reduction of electric losses and the concentration of the losses to places favorable for cooling. 3) to analyze the strength of the fittings at assembly and at high speeds.