No description available.

No description available.

No description available.

No description available.

This project is focused on two objectives: X-Y displacement sensor design and design of switched reluctance motor with a magnetic bearing instead of mechanic bearings to support the rotor at one end. At the other end, a mechanical bearing is still used. Two types of design of low cost sensor for rotor displacement detection are presented. Both of them have very simple structure, which gives very low cost. The first presented sensor has the rotor with 12 poles permanent magnets on its surface. The experimental performance shows this sensor can detect the displacement, but it is not suitable for bearingless control because it doesn't have smooth output and can't work when motor stops. The second sensor design has a solid steel rotor and the experimental performance shows it can detect the displacement for bearingless control in terms of quick response and low cost. A magnetic bearing is realized in a single phase switched reluctance motor. The basic principle is that besides main winding, a radial force winding is employed on each stator tooth, which can generate the flux to balance the radial force in the airgaps so that the rotor can be self-supported. Mathematic analysis and simulation are pretend. The experimental results show that magnetic bearing can support the rotor in the central position regardless of the external force (within 12 N) acting on the rotor shaft. Bearingless control on a two phase switched reluctance motor with only one bearing is also designed. In the experiment, a proper switching point is chosen, which is for the control switching between two phases. Experimental results show that rotor can run with only one magnetic bearing support at 250 rpm. Although the running speed is very low, it is an important step for further research on bearingless control design.

A time-domain six-parameter model is adopted to simulate the vibration behaviour of various rubber-isolators at constant temperature and preload over the frequency range of 0.05-25 Hz. The model consists of three components based on a nonlinear parabolic spring, a fractional-derivative-based springpot, and a smooth-slip friction element. The adopted mode working in one-dimensional manner is capable of generating force as a function of displacement.

An in-depth analytical, numerical and experimental study investigating the vibrational characteristics of a rotor system with a clearance is the main objective of this thesis.  The mathematical modelling of a two degrees-of-freedom rotor system was done based on the Jeffcott rotor model.  The physical model assumes a situation where gyroscopic forces are neglected and concentrates on the dynamic responses caused by interactions between a whirling rotor and a massless snubber ring, which has much higher stiffness than the rotor. Two analytical methods for calculating nonlinear dynamic responses of the rotor system are devised in order to obtain robust analytical solutions maintaining high computational accuracy. To unveil the global dynamics of the rotor system different nonlinear dynamics analysis techniques in the form of time trajectories, phase portraits, bifurcation diagrams, Poincaré maps, power spectrum analysis, basins of attraction and parameter planes are employed.  In particular, the effect of preloading on the system dynamics was also investigated. Based on analysis of the nonlinearity of the restoring forces, the Jeffcott rotor model was justified in comparison with the squeeze film damping journal using the short bearing approximation. Design and basic modification to the existing experimental rig was carried out in order to create a ‘smart’ structure to effectively control the system responses using an ER damper, Shape Memory Alloys composite beams, eccentricity controllers and forcing frequency.  Extensive experimental studies are undertaken to explore the system dynamics and justify the computational model.

No description available.

Several sophisticated procedures for balancing flexible rotors have been developed during the past two decades. For a variety of reasons, none of these methods has gained general acceptance by practicing balancing engineers. Some of these balancing techniques require a great deal of expertise from the operator. This thesis is dedicated to the research of flexible rotor balancing techniques, and aims to apply some advanced techniques to the field of high-speed rotor balancing. Significant progress in balancing methods for flexible rotors can be achieved by the improvement and optimization of existing balancing techniques. Experimental tests were conducted to demonstrate the ability of the influence coefficient method to achieve precise balance of flexible rotors. Various practical aspects of flexible- rotor balancing were investigated. Tests were made on a laboratory quality test rig having a 3.6 m long rotor representing a High Pressure Turbine (H.P.T) (10.1 kg)(43.767 cm), a Low Pressure Turbine (L.P.T) (43.922 kg) (113.698 cm) and a Generator Rotor (G. Rotor) (71.611kg) (146.413 cm) and covering a speed range up to 6000 rpm. A specific data acquisition system has been developed for use in a high-speed rotor balance facility. Special measurement requirements for this facility include order-tracked vibration measurements and phase angle data. The data acquisition system utilizes dual high-speed computer systems to share the tasks of measurement data processing, and results display. A study of balancing errors is systematically discussed in detail from the view point of increasing the balancing precision. The methods for controlling and reducing these errors are also discussed. Both the qualitative and quantitative analyses of balancing errors are performed as the guide to reduce the error and improve the balancing quality. The thesis also presents the theoretical background and the techniques necessary to the procedure to balance the flexible rotor. A trim balancing method was developed to expand the implementation of flexible rotor balancing. A computer program has been written which generates influence coefficient from measured motions and goes on to predict the correction mass. The vibration has been measured at several locations and speeds and the results have been used to (a) ensure that the vibration levels were not excessive as the rotor speed increased and (b) to calculate the balance correction weights using the traditional influence coefficient method and a least squares influence coefficient method. The procedure developed was verified using an experimental rotor rig. The successful application of the procedure to the balancing of this rotor demonstrates that balancing using Singular Value Decomposition, QR Factorization, and QR Factorization combined with SVD and new trim balancing method is not only a theoretical but also a practical possibility. The Moore-Penrose generalized inverse has been employed to solve the problem. The dynamic characteristics of the rotor rig, however, were somewhat limited and did not cover all the possibilities considered during the project. Therefore, a more complete numerical example was also successfully solved using the computer model of a rotor with characteristics similar to those of a real turbine by using a finite element software package called ANSYS.

Compressor blades are subtle aerodynamic shapes designed after years of research and insight. They inevitably show deviations from their desired shapes due to manufacturing errors, erosion or foreign object damage. In the present study we focus on seeking compressor blade geometries, that are robust in performance in the presence of geometric uncertainty. Sophisticated tools for representing and propagating uncertainty are employed. Novel method for modeling eroded blade geometry and simulating manufacturing variations with process capability data are presented. These are combined with an automatic meshing routine and a high fidelity viscous flow solver for performance analysis. A combination of Design of Experiment techniques and Gaussian Process emulators are employed to develop efficient surrogate models for uncertainty analysis and exploring the design space. Efficient multiobjective optimization based robust design methodologies are presented. The robust design methods in conjunction with the surrogate model are used to seek blades that have less variation in performance in the presence of erosion and manufacturing variations. Main effects and sensitivity analysis are also performed to understand the effect of each noise variable on the performance. The performance of the robust blades obtained are compared to that of deterministic optimal blades in the presence of the uncertainties. The robust optimal blades exhibit considerably less variability and mean shift in performance as compared to the optimal blades. Finally, a probabilistic framework is developed to deal with randomness in objectives during multiobjective optimization and is applied in conjunction with Gaussian Process emulators for robust design.