Thesis (M.S.)--University of Wisconsin--Madison, 1962. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 32).

The parallel surface thrust bearing has been studied both theoretically and experimentally. The general equations governing the laminar flow of a Newtonian fluid are presented and suitably reduced to describe the flow of lubricant through a plain collar bearing. A computer solution of the resulting equations has been obtained in which the variations, of density and viscosity with temperature are accommodated and the circumferential leakage of oil from the bearing is recognised. The resulting performance curves indicate that useful load carrying capacities, produced by a 'thermal wedge' effect, are possible with parallel surface thrust bearings. A series of tests was carried out on a three inch diameter bearing operating at speeds ranging from 15,000 to 19,000 r.p.m. The results confirm that hydrodynamic lubrication may be achieved with a parallel surface thrust bearing. The experimental values obtained for the load carrying capacity and the coefficient of friction were both less than the theoretical predictions. The discrepancies appear to be caused, for the most part, by an increase in the oil temperature resulting from entrainment of the lubricant in the bearing. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

No description available.

No description available.

This thesis evaluates the application of Reynolds equation in calculating fluid film forces (FFFs) in circumferential groove journal bearings (CGJBs) with both balanced and unbalanced rotors. The existing rig was fabricated at UNSW for that purpose. Unfortunately the rig was unsuitable because it was unstable at speeds as low as 500 rpm. This occurred because, when designing the rig, the traditional ??-film cavitation boundary model (CBM) was used. Consequently a modified cavitation boundary model (MCBM) was proposed which correctly predicted the instability threshold of the rig. Using the MCBM, new bearings were installed and the modified rig was stable in the required speed range up to 2400 rpm. Two existing computer programs to calculate bearing stiffness and damping coefficients and FFFs were modified for the purposes of this study. In addition, only dynamic components (AC components) of experimental FFFs could be measured accurately. The vertical mean value (DC component) of experimental FFF was approximated to the vertical reaction force and the horizontal DC component of experimental FFF was approximated to zero at each bearing. This thesis concludes that the numerical solution of Reynolds equation to calculate DC components of FFFs in a CGJB is valid with a proper selection of CBM. The agreement of AC components of the FFFs were good with a balanced rotor, but were poor with an unbalanced rotor. The modified CBM is more accurate than the existing ??-film CBMs. The cavity region is important to obtain accurate numerical results and depends on test conditions, bearing dimensions, etc. To design for critical speeds, cavitation pressure could be either oil vapour pressure or atmospheric pressure; however, to design for stability, cavitation pressure should be oil vapour pressure, or even much lower. Two halves of a CGJB carried different loads because of misalignment and different clearances. In addition, reducing length and increasing clearance significantly increased the stability of the rig. Finally, to obtain perfect agreement between numerical and experimental FFFs, short bearings and a smaller clearance ratio are strongly recommended. A special design to measure cavitation pressure is suggested.

The Electron Energy Corporation (EEC) along with National Aeronautics and Space Administration (NASA) in collaboration with Vibration Control and Electro mechanics Lab (VCEL), Texas A & M University, College Station, TX are researching on high temperature permanent magnet based magnetic bearings. The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two radial bearings, one axial thrust bearing and two catcher bearings. The test rig that the catcher bearing is inserted in is the first ultra-high temperature rig with permanent magnet biased magnetic bearings and motor. The magnetic bearings are permanent magnet based which is a novel concept. The Graphalloy bearings represent a new approach for ultra-high temperature backup bearing applications. One of the main objectives of this research is to insure the mechanical and electrical integrity for all components of the test rig. Some assemblies and accessories required for the whole assembly need to be designed. The assembly methods need to be designed. The preliminary tests for coefficient of friction, Young's modulus and thermal expansion characteristics for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB. The assembly of the test rig was completed successfully by developing assembly fixtures and assembly methods. The components of the test rig were tested before assembly. Other necessary systems like Sensor holder system, Graphalloy press fit system were designed, fabricated and tested. The catcher bearing material (Graphalloy) was tested for coefficient of friction and Young's modulus at room and high temperatures. The rotor drop was simulated by deriving a dynamic model, to study the effect of system parameters like clearance, coefficient of friction, negative stiffness, initial spin speed on system behavior. Increasing the friction increases the backward whirl and decreases the rotor stoppage time. Increasing the clearance reduces the stoppage time and increases the peak bearing force. Increasing the initial spin speed increases the rotor stoppage time. The maximum stress encountered for as built conditions is more than allowable limits.

This thesis evaluates the application of Reynolds equation in calculating fluid film forces (FFFs) in circumferential groove journal bearings (CGJBs) with both balanced and unbalanced rotors. The existing rig was fabricated at UNSW for that purpose. Unfortunately the rig was unsuitable because it was unstable at speeds as low as 500 rpm. This occurred because, when designing the rig, the traditional ??-film cavitation boundary model (CBM) was used. Consequently a modified cavitation boundary model (MCBM) was proposed which correctly predicted the instability threshold of the rig. Using the MCBM, new bearings were installed and the modified rig was stable in the required speed range up to 2400 rpm. Two existing computer programs to calculate bearing stiffness and damping coefficients and FFFs were modified for the purposes of this study. In addition, only dynamic components (AC components) of experimental FFFs could be measured accurately. The vertical mean value (DC component) of experimental FFF was approximated to the vertical reaction force and the horizontal DC component of experimental FFF was approximated to zero at each bearing. This thesis concludes that the numerical solution of Reynolds equation to calculate DC components of FFFs in a CGJB is valid with a proper selection of CBM. The agreement of AC components of the FFFs were good with a balanced rotor, but were poor with an unbalanced rotor. The modified CBM is more accurate than the existing ??-film CBMs. The cavity region is important to obtain accurate numerical results and depends on test conditions, bearing dimensions, etc. To design for critical speeds, cavitation pressure could be either oil vapour pressure or atmospheric pressure; however, to design for stability, cavitation pressure should be oil vapour pressure, or even much lower. Two halves of a CGJB carried different loads because of misalignment and different clearances. In addition, reducing length and increasing clearance significantly increased the stability of the rig. Finally, to obtain perfect agreement between numerical and experimental FFFs, short bearings and a smaller clearance ratio are strongly recommended. A special design to measure cavitation pressure is suggested.

No description available.

This thesis presents an interactive computer-graphics geometry interface that simplifies the tapered roller bearing selection procedure. An applications program has been developed that links the CADAM data base to SELECT-A-NALYSIS (SAN), Timken's bearing selection and analysis program. The independent modular format of the SAN preprocessor eliminates the ambiguity and difficulty associated with conventional bearing selection routines. Interactive-graphic menu selection allows program logic to be followed while design geometry is selected from a CADAM model. In addition to the discussion of the program development and structure, step-by-step instructions for an example problem are provided. Complete program listings are also supplied to facilitate future additions and modifications to the preprocessor. / M.S.

Methods are presented for parameter identification of an annular gas seal on a flexiblerotor test rig. Dynamic loads are applied by magnetic bearings (MBs) that support the rotor. MB forces are measured using fiber-optic strain gauges that are bonded to the poles of the MBs. In addition to force and position measurements, a finite element (FE) rotor model is required for the identification algorithms. The FE rotor model matches free-free characteristics of the test rotor. The addition of smooth air seals to the system introduces stiffness and damping terms for identification that are representative of reaction forces in turbomachines. Tests are performed to experimentally determine seal stiffness and damping coefficients for different running speeds and preswirl conditions. Stiffness and damping coefficients are determined using a frequency domain identification method. This method uses an iterative approach to minimize error between theoretical and experimental transfer functions. Several time domain approaches are also considered; however, these approaches do not produce valid identification results. Stiffness coefficients are measured using static test results and an MB current and position based model. Test results produce seal coefficients with low uncertainties for the frequency domain identification method. Static test uncertainties are an order of magnitude larger, and time domain attempts fail to produce sealIn addition to the primary identification research, an investigation of the relationships between MB force, strain, and magnetic field is conducted. The magnetic field of an MB is modeled using commercial FE software. The magnetic field model is used to predict strain measurements for quasi-static test conditions. The strain predictions are compared with experimental strain measurements. Strain predictions agree with experimental measurements, although strain is typically over-predicted. coefficient measurements.