The Rocketdyne Multifunction Tester. Part 1: Test Method

The Rocketdyne Multifunction Tester is a general purpose test apparatus which utilizes axial and radial magnetic bearings as shaft excitation devices. The tester is modular in design so that different seal and bearing packages can be tested on the same test stand. The tester will be used for rotordynamic coefficient extraction, as well as life and fluid/material compatibility evaluations. Use of a magnetic bearing as a shaft excitation device opens up many possibilities for shaft excitation and rotordynamic coefficient extraction. In addition to describing the basic apparatus, some of the excitation and extraction methods are described. Some of the excitation methods to be discussed include random, aperiodic, harmonic, impulse and chirp

Numerical, analytical, experimental study of fluid dynamic forces in seals

NASA/Lewis Research Center is sponsoring a program for providing computer codes for analyzing and designing turbomachinery seals for future aerospace and engine systems. The program is made up of three principal components: (1) the development of advanced three dimensional (3-D) computational fluid dynamics codes, (2) the production of simpler two dimensional (2-D) industrial codes, and (3) the development of a knowledge based system (KBS) that contains an expert system to assist in seal selection and design. The first task has been to concentrate on cylindrical geometries with straight, tapered, and stepped bores. Improvements have been made by adoption of a colocated grid formulation, incorporation of higher order, time accurate schemes for transient analysis and high order discretization schemes for spatial derivatives. This report describes the mathematical formulations and presents a variety of 2-D results, including labyrinth and brush seal flows. Extensions of 3-D are presently in progress

Final Design Report Cal Poly Wind Power - Balancing System

The Cal Poly Wind Power club is anticipating joining the annual Collegiate Wind Competition in the year 2021. This competition hosts schools from all around the country, who meet and compete against each other by testing the wind turbines they have made throughout the academic school year. Tasks included in the competition test the wind turbine’s efficiency, power generation, overall design, and stability in extreme conditions. Cal Poly is planning to implement a formal balancing system to support their 2021 wind turbine. Our senior project team undertook mitigating mass imbalance in the wind turbine; mass imbalance occurs when the center of mass of a rotating object does not lie on the axis of rotation. Our project’s original goal was to develop a balancing system to minimize mass unbalance in the wind turbine’s rotor assembly and optimize power collection while keeping the turbine safe to operate. While we were able to develop this mechanism and provide design documentation to the CPWPC, we were unable to balance the competition wind turbine. In this report, we discuss the preliminary research conducted regarding wind turbine rotary systems and rotational imbalances. Furthermore, we will break down our understanding of the project and our approach to completing it, as well as our ideation and down-selection processes. Then, we will detail our plans to cheaply manufacture and accurately balance the wind turbine. Finally, we will outline the next steps needed to thoroughly verify the final design, as well as officially balance the completed 2021 wind turbine

System Identification Methods for Dynamic Testing of Fluid-Film Bearings

There are various system identification approaches typically used to extract the rotordynamic coefficients from simultaneously measured dynamic force and motion signals. Since the coefficient values extracted can vary significantly as a function of the system identification approach used, more attention is needed to treat this issue than is typically included in the rotor dynamics literature. This paper describes system identification and data reduction methods used for extracting rotordynamic coefficients of fluid-film journal bearings. Data is used from a test apparatus incorporating a double-spoolshaft spindle which permits independent control over the journal spin speed and the frequency of an adjustable-magnitude circular orbit, for both forward and backward whirling. For example, a least squares linear regression on the force-displacement equations of the experiment provides only one of the rational approaches to extract the anisotropic rotordynamic coefficients (stiffness, damping and fluid inertia effects). Rotordynamic coefficients are also extracted with both first and second order orbital frequency dependencies. To assess the quality of the measured signals, coherence functions are calculated to relate the time-averaged input motion signals and the time-averaged output force signals

Rotordynamic Instability Problems in High-Performance Turbomachinery, 1986

The first rotordynamics workshop proceedings (NASA CP-2133, 1980) emphasized a feeling of uncertainty in predicting the stability of characteristics of high-performance turbomachinery. In the second workshop proceedings (NASA CP-2250, 1982) these uncertainities were reduced through programs established to systematically resolve problems, with emphasis on experimental validiation of the forces that influence rotordynamics. In third proceedings (NASA CP-2338, 1984) many programs for predicting or measuring forces and force coefficients in high-performance turbomachinery produced results. Data became available for designing new machines with enhanced stability characteristics or for upgrading existing machines. The present workshop proceedings illustrates a continued trend toward a more unified view of rotordynamic instability problems and several encouraging new analytical developments

Rotordynamic Instability Problems in High-Performance Turbomachinery, 1990

The present workshop continues to report field experience and experimental results, and it expands the use of computational and control techniques with the integration of damper, bearing, and eccentric seal operation results. The intent of the workshop was to provide a continuing impetus for an understanding and resolution of these problems

Hybrid air bearings for high speed turbo machinery

This PhD project is set out to develop a type of hybrid journal air bearings with reduced reliance on the supply of compressed air for mobile turbomachinery applications. The research work covers hydrostatic and hybrid journal air bearings with non-compliant clearance boundaries. The approach adopted combined numerical analysis based on CFD and experimental verification of the designs. The research can be divided into three sections. In the first section, numerical approaches to model hydrostatic and hybrid journal air bearings with a fixed clearance boundary were developed based on finite difference method (FDM) and finite volume method (FVM) respectively. In the second and third section, theoretical and experimental studies were performed on hydrostatic and hybrid journal air bearings. Performance of the bearings was investigated in non-rotational and rotational conditions. The analysis on stability and natural frequencies of rotor bearing system was performed using the linear bearing model. The unbalance responses of the rotor in the test rig were predicted using non-linear transient analysis and measured experimentally from 50k rpm to 120k rpm in rotor speed. Through the theoretical and experimental investigations of the hybrid journal air bearings, the objectives of the project have been implemented and the aims have been met

Fluid bearing spindles for data storage devices

Ph.DDOCTOR OF PHILOSOPH

On the Reduction of the Driving Force in Shear-driven Flows

In shear-driven flows, an external driving force is needed to maintain the relative movement of horizontal plates. This thesis presents a systematic analysis on using spatially periodic heating and grooved surfaces to control this force. It is found that the use of periodic heating creates a buoyancy-driven effect that always reduces this force. The use of proper heating may even lead to the complete elimination of this force. It is further found that the use of isothermal grooved surfaces always enhances flow resistance, resulting in an increase of this force. When grooves and heating are applied together, their interaction induces a horizontal pressure force that can either increase or decrease the driving force, depending on the relative positions of the groove and heating patterns. Mechanisms leading to such changes of the driving force are discussed