Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 18 of 18 for “"rotordynamics"”.
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MEMS turbomachinery rotordynamics : modeling, design and testing
One of the major challenges encountered for the successful operation of high-power-density micro-devices lies in the stable operation of the bearings supporting the high-speed rotating machinery. This thesis presents the analysis, design, microfabrication, testing and operation of high speed …
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Dynamic Stability Evaluation of an Automotive Turbocharger Rotor-Bearing System
… how the linear analysis of a turbocharger rotordynamics can be very beneficial for the design evaluation and maintenance purposes.
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Development of a high power density rotor
… to high speed, and thin radial builds that affect rotordynamics. Similarly, the design creates thermal challenges, of which extracting heat from a small geometry, and the difficulty of estimating windage losses because of the high speed and large diameter, are two. These challenges have been …
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Computer-aided design software for rotor dynamics analysis
… rotor in isotropic bearings has been developed. Rotordynamics theory related to this research work is studied including synchronous unbalance response, critical speed, gyroscopic effect, critical speed map, and stability. The method of solution is based on the Transfer Matrix approach containing …
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Testing of a microrocket engine turbopump
… Structural concerns have been addressed. Rotordynamics issues have been investigated. Pumping tests were performed and have paved the way toward an effective pressure rise. The innovative rotor arrangement with coplanar pump and turbine was validated. Dual phase operation involving water …
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Development of a microfabricated turbine-driven air bearing rig
… research into micro-fabricated gas bearings and rotordynamics. The process flow involves the use of 16 masks, 9 aligned deep reactive ion etching (ORIE) steps, aligned fusion bonding of a 5 wafer stack, and laser assisted etching. The device has been successfully fabricated, and the fabrication …
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Developments on Electrodynamic Levitation of Rotors
… complex coordinate representation, typical in rotordynamics, in order to enable easy integration of the bearing's model with different rotordynamic models. An experimental validation of the model is carried out for homopolar configurations. The study of the dynamics of rotors on electrodynamic …
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Rotordynamic assessment for a permanent magnet synchronous motor
High speed and high rotor tip-speed, in particular, combined with high magnetic and electrical loading, are key enablers for obtaining high specific power in electric machines. The rotor described in this thesis pushes the tip speed to about 80% of the speed of sound. An outer rotor design with a …
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Development of a high-speed rotating bar mechanism
A high-speed rotary device was designed to generate shock waves in a transonic blowdown wind tunnel cascade. The rotary device (Rotating Bar Mechanism) will be used in research conducted at Virginia Tech to study the effects of unsteady aerodynamic flow and heat transfer (resulting from upstream …
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Synchronous Thermal Instability Evaluation of Medium Speed Turbocharger Rotor-Bearing Systems
Rotors in fluid-film bearing supported turbomachinery are known to develop elliptical orbits as a result of rotor-bearing interactions, mass unbalance within the rotor, gravitational bending of the shaft and external excitation. In synchronous whirl, where the speed at which the shaft travels about …
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Stability Analysis of a Turbocharger for Marine Diesel Engine Service
Rotor stability is essential to the life span of any piece of rotating machinery; it becomes increasingly critical in high-speed machinery such as turbochargers. Large turbochargers, such as those found in marine diesel propulsion engines where the rotor alone often exceeds forty pounds, require …
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Computational Fluid Dynamic and Rotordynamic Study on the Labyrinth Seal
The labyrinth seal is widely used in turbo machines to reduce leakage flow. The stability of the rotor is influenced by the labyrinth seal because of the driving forces generated in the seal. The working fluid usually has a circumferential velocity component before entering the seal; the ratio of …
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Evaluation of the Effectiveness of an Active Magnetic Damper (AMD) in Damping Subsynchronous Vibrations in a Flexible Rotor
Subsynchronous vibrations such as those caused by rotor instability represent one of the most harrowing scenarios of rotor vibration. They are related to a great diversity of destabilizing forces and some of them are not well understood yet. Therefore, special attention must be paid to this type of …
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Development of a Rotordynamic Signal Processing MATLAB Interface and a Two-Disk Rotor Model
<p>Using MATLAB and a National Instruments data acquisition card, a signal processing program meant to monitor the behavior of rotordynamic systems in real-time was developed and tested. By using traditional analysis methods in this field of engineering, commonly desired data representations such …
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Surface Patterning and Rotordynamic Response of Annular Pressure Seals Used in Turbomachinery
Rotordynamic instability problems in turbomachinery have become more important in recent years due to rotordynamic components with higher speeds and higher power densities. These features typically lead to increased instability risk in rotor dynamic components as fluids-structure interactions take …
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Measured and Predicted Rotor-Pad Transfer Functions for a Rocker-Pivot Tilting-Pad Journal Bearing
Many researchers have compared predicted stiffness and damping coefficients for tilting-pad journal bearings (TPJBs) to measurements. Most have found that direct damping is consistently overpredicted. The thrust of this research is to explain the difference between measured and predicted stiffness …
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Rotordynamic Analysis of Theoretical Models and Experimental Systems
<p>This thesis is intended to provide fundamental information for the construction and</p> <p>analysis of rotordynamic theoretical models, and their comparison the experimental</p> <p>systems. Finite Element Method (FEM) is used to construct models using Timoshenko</p> <p>beam elements with viscous …