Vibration detection in turbomachinery using non-contacting sensors

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (p. 103-105).Recent developments have seen the introduction of multiple Eddy Current Sensors (ECS) into turbomachinery. These sensors employ an active magnetic field to monitor each blade as it passes the sensor. They generate an electrical signal proportional to the distance of a blade from the sensor. Existing algorithms extract two pieces of information from the ECS signature, signal magnitude and signal zero crossing time. The signal magnitude is used to find tip clearance, and the zero crossing time is used to estimate vibrational parameters over the course of multiple revolutions. These techniques fail to exploit the majority of the information contained in the ECS signal. In this research, a novel residue characterization algorithm was developed that processes the full ECS pulse to produce a residue. The residue is a speed independent representation of differences between a baseline ECS pulse and an experimental ECS pulse. A mathematical model of the relationship between blade displacement and residue was developed. Empirical data collected with the MIT spin pit were used to verify convergence of the model with the residue characterization algorithm. This strongly suggests blade vibration can be deduced using the residue characterization method with a single ECS sensor.by Eric D. Cohen.M.Eng

Orbit Transfer Rocket Engine Technology Program: Advanced engine study, task D.1/D.3

Concepts for space maintainability of OTV engines were examined. An engine design was developed which was driven by space maintenance requirements and by a failure mode and effects (FME) analysis. Modularity within the engine was shown to offer cost benefits and improved space maintenance capabilities. Space operable disconnects were conceptualized for both engine change-out and for module replacement. Through FME mitigation the modules were conceptualized to contain the least reliable and most often replaced engine components. A preliminary space maintenance plan was developed around a controls and condition monitoring system using advanced sensors, controls, and condition monitoring concepts. A complete engine layout was prepared satisfying current vehicle requirements and utilizing projected component advanced technologies. A technology plan for developing the required technology was assembled

Structures Division 1994 Annual Report

The NASA Lewis Research Center Structures Division is an international leader and pioneer in developing new structural analysis, life prediction, and failure analysis related to rotating machinery and more specifically to hot section components in air-breathing aircraft engines and spacecraft propulsion systems. The research consists of both deterministic and probabilistic methodology. Studies include, but are not limited to, high-cycle and low-cycle fatigue as well as material creep. Studies of structural failure are at both the micro- and macrolevels. Nondestructive evaluation methods related to structural reliability are developed, applied, and evaluated. Materials from which structural components are made, studied, and tested are monolithics and metal-matrix, polymer-matrix, and ceramic-matrix composites. Aeroelastic models are developed and used to determine the cyclic loading and life of fan and turbine blades. Life models are developed and tested for bearings, seals, and other mechanical components, such as magnetic suspensions. Results of these studies are published in NASA technical papers and reference publication as well as in technical society journal articles. The results of the work of the Structures Division and the bibliography of its publications for calendar year 1994 are presented

SIRM 2017

This volume contains selected papers presented at the 12th International Conference on vibrations in rotating machines, SIRM, which took place February 15-17, 2017 at the campus of the Graz University of Technology. By all meaningful measures, SIRM was a great success, attracting about 120 participants (ranging from senior colleagues to graduate students) from 14 countries. Latest trends in theoretical research, development, design and machine maintenance have been discussed between machine manufacturers, machine operators and scientific representatives in the field of rotor dynamics. SIRM 2017 included thematic sessions on the following topics: Rotordynamics, Stability, Friction, Monitoring, Electrical Machines, Torsional Vibrations, Blade Vibrations, Balancing, Parametric Excitation, and Bearings. The papers struck an admirable balance between theory, analysis, computation and experiment, thus contributing a richly diverse set of perspectives and methods to the audience of the conference

Application of Active Magnetic Force Actuator for Control of Flexible Rotor System Vibrations

The purpose of this work was to develop and experimentally demonstrate a novel approach to minimize lateral vibrations of flexible rotor. The applied feed forward control approach employed magnetic force actuator to inject a specially designed force to counteract the rotor unbalance force. By specific selection of frequency and phase as functions of the rotor running speed and rotor natural frequency, the proposed simplified injection waveform has been shown to be effective both in reducing the rotor\u27s vibrations and for hardware implementation. A model of the test rig was constructed using the finite element (FE) method and was validated using experimental data. The effectiveness of the proposed current injection was numerically simulated with FE model and experimentally validated using a residual unbalance force. It was noticed that at a selected constant running speed, just below the first rotor critical speed, the rotor vibrations were reduced approximately by 90 . The method was also implemented during the speed ramp test, which passes through the first critical speed. In this test the proposed force injection also reduced vibrations at various rotor speeds. These results agree well with the results of simulatio

International Symposium on Magnetic Suspension Technology, Part 1

The goal of the symposium was to examine the state of technology of all areas of magnetic suspension and to review related recent developments in sensors and controls approaches, superconducting magnet technology, and design/implementation practices. The symposium included 17 technical sessions in which 55 papers were presented. The technical session covered the areas of bearings, sensors and controls, microgravity and vibration isolation, superconductivity, manufacturing applications, wind tunnel magnetic suspension systems, magnetically levitated trains (MAGLEV), space applications, and large gap magnetic suspension systems