Simulation tool for determining dynamic characteristics of high speed cryogenic rotor bearing systems by comparison with experiments

Most cryogenic turboexpander rotors are gas bearing supported high speed machines with a small size turbine at one end and a brake compressor at the other end. It is important to correctly predict the critical speeds of these rotors to enable them to quickly pass through these speeds during coasting up to design/service speed and also to define the stable operation band sufficiently far from the cntical speeds. The present paper describes the development of a simulation tool for correct determination of the dynamic characteristics of a rotor bearing system. Transfer matrix method is used in the program for computing the dynamic characteristics.