Advanced vibration control measures for high performance rotating machines

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Overview: Aero-Engine Rotor Dynamics invariably plays a central role in modern aero-engine design and there is a tremendous opportunity for a new-generation of approaches as the old rule-based design methods fade away and as an outgoing generation of rotordynamics is retiring. Background summary Damping is an invaluable tool in all vibration contexts where it is possible that some excitation frequency may coincide with system resonance. In the context of aero-engines, that means when the engine rotor spin speed is the same as a so-called "critical speed". The main existing approach to damping is to exploit squeeze-film dampers (SDFs). Many of the options that engineers would naturally take for other vibration problems are not applicable in aero-engines because the dampers must be tolerant to reasonably high temperatures and they must not degrade over thousands of hours of operation. Aim The key research objectives of this PhD study are: Understand the operation of existing SFDs better Develop an improved insight into how the intrinsic highly non-linear behaviour of SFDs manifests itself inside the vibration characteristics of aero-enginesAchieve insight into the distribution of vibration responses that can arise from a single engine design based on small variations in geometry and material properties Propose and analyse design evolutions / revolutions for SFDs or other damping provisions that will improve the robustness of future aero-engine designs by delivering more consistent performanceObtain further experimental evidence to support the above. Methods and timescale The research will be conducted at the University of Nottingham within the Gas Turbines and Transmissions research centre - a research group of 50 people. It will be supported actively by experts from Rolls-Royce. The project is essentially timely at present because a new generation of aero-engines is being engineered that will have more critical speeds within the range of normal running speeds. As such, there is significant scope for this work to make a real difference to future designs.