Experimental Measurements of Turbomachinery Rotordynamics, Component Performance, and Dynamic Control at ROMAC - A Review

摘要

Rotordynamics play a critical role in the reliable operation of high-speed turbomachinery. Modern trends in the field of rotating machinery all point to the same common goal: users want to be able to do more with their machines. This results in a push for a wide range of design modifications and improvements including longer shafts to accommodate more fluid stages, higher rotating speeds, higher fluid pressures, and larger rotors for increased capacity. This evolution in machine design poses a number of challenges from a rotordynamics standpoint including more flexible rotors, larger bearing loads, and higher levels of destabilizing forces which can lead to the ultimate failure of the machine (1). Understanding the rotordynamic performance of a machine is essential to its final design and smooth operation. Keeping overall vibration levels low and the stability of vibrational modes that can be excited high ensures a reliable design, however this performance is affected by nearly every major component in the machine. Impeller blades and fluid seals produce destabilizing cross-coupled stiffness forces which reduce the stability of the machine while fluid film bearings and magnetic bearings provide damping to the system and control the machine vibration, hence the ability to predict the performance of these components is also critical to ensuring a proper design. However, much uncertainty still exists in the accurate prediction of the forces generated by these components (2). Therefore, experimental test rigs used to validate theoretical and computational predictive models are extremely important to eliminating the remaining sources of uncertainty in this field as these limit how far boundaries can be pushed in new machine designs.