Rotordynamic Analysis of a Power Turbine Including Support Flexibility Effects

Power turbines are commonly used in the oil and gas industries as mechanical drives of process equipment such as centrifugal compressors or electrical generators. Power turbine rotordynamic design analysis is important because there may be interaction between the rotor and the structure, including the baseplate where they are mounted. This paper presents the results of the dynamic analysis of a power turbine considering the turbine frame, gas generator and baseplate. A large finite element model (FEM) of the assembly is used to generate transfer functions representing the dynamics of these components acting at the rotor bearing locations. The transfer function information is then used in a dedicated rotordynamic program to perform parametric studies and provide recommendations for the optimum power turbine bearing and baseplate configurations that meet all applicable industrial specifications. Predictions from a complete rotor-structure finite element model confirm the results from the dedicated rotordynamic program using transfer functions, showing that this simplified model can be used to satisfactorily study the system dynamics.