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Full-Text Articles in Engineering

Turbomachine Stability And Forced Response Prediction, Leland Bert Clark Dec 1992

Turbomachine Stability And Forced Response Prediction, Leland Bert Clark

Open Access Theses

A mathematical model is developed and utilized to analyze turbomachine cascade flutter and forced response. The flutter boundary, defined as the largest value of reduced frequency at which flutter occurs for a given cascade, was evaluated for single degree of freedom torsional oscillation as well as coupled bending and torsional oscillations. The maximum amplitude of forced response in bending and torsion was also considered. The unsteady aerodynamic lift and moment coefficients were determined from unsteady aerodynamic flow models for subsonic flow, supersonic flow with a subsonic axial component and supersonic axial flow. The effect of changing the Mach number, stagger ...


Laser Doppler Velocimetry Research Of The Blowby Gas Characteristics In An Internal Combustion Engine, Coffill Dec 1992

Laser Doppler Velocimetry Research Of The Blowby Gas Characteristics In An Internal Combustion Engine, Coffill

Master's Theses

The project was designed to measure a reciprocating engine fluid flow (blowby gases past the piston rings) using a laser doppler velocimeter (LDV). Blowby gases were obtained by introducing compressed air into an engine cylinder (piston held at TDC) to simulate engine combustion pressures. Beginning the proposed research included starting an LDV/reciprocating engine laboratory at Western Michigan University and determining the limits of the measurement devices (LDV system in particular).

The limitations which were found in the LDV system only allowed for limited results of in cylinder optical measurements. The results obtained were for cylinder pressures below 0.6 ...


Design For Productivity Using Gd&T, Srihari G. Acharya Oct 1992

Design For Productivity Using Gd&T, Srihari G. Acharya

Theses

No abstract provided.


Errors In Constant-Velocity Shaft Couplings, Philip M. Remington Oct 1992

Errors In Constant-Velocity Shaft Couplings, Philip M. Remington

Theses

A Multiloop spatial system of rotations is used to represent a shaft coupling, allowing a transmission plane which may deviate from the plane of symmetry to be specified. The plane of transmission, for intersecting input and output shaft axes, is the locus of intersections of screw axes that compose the system. By prescribing the transmission plane outside of the plane of symmetry (commonly called the "homokinetic plane" or "bisecting plane") to pecified orientations, a phase shift between the input and output shaft rotational displacements will he quantified. The rotational phase shift between the input and output shafts can be evaluated ...


Expert System For The Injection Molding Of Engineering Thermoplastics, Tzy-Cherng Jan Oct 1992

Expert System For The Injection Molding Of Engineering Thermoplastics, Tzy-Cherng Jan

Dissertations

Injection molding of engineering thermoplastics is the most widely used manufacturing method in industry. It is a priority to maintain a deviation-free operating environment to ensure high quality, low cost manufacture. An expert system for the injection molding of engineering thermoplastics has been investigated. The system can be used to attenuate the deviations experienced during the injection molding of engineering thermoplastics. The system is coded in C programming language.

The resolution procedures of this system include two stages such as the definition of declarative knowledge and the procedure of corrective actions. In the definition of declarative knowledge, all of the ...


A Study Of Annular Slurry Jet For Abrasive Waterjet Cutting, Thomas Kuriakose Oct 1992

A Study Of Annular Slurry Jet For Abrasive Waterjet Cutting, Thomas Kuriakose

Theses

The objective of this project is to study the performance of an annualr slurry jet nozzle for abrasive waterjet cutting. This nozzle has been invented by Avraham. Harnoy, Department of Mechanical Engineering, NJIT and presented to the patent committee of NJIT in May 1990. This study includes design and development of prototyes and testing of their performance. Moreover, it includes initial theoretical study of the flow behavior. The idea is based on the merging of a high velocity pure waterjet with an annular jet of a slurry of water and abrasives at low velocity. The two jets merge outside the ...


Design Of Nozzle Contours For The Pwt 16-Ft Transonic Wind Tunnel, William Everett Milam Aug 1992

Design Of Nozzle Contours For The Pwt 16-Ft Transonic Wind Tunnel, William Everett Milam

Masters Theses

The nozzle contours of the Tunnel 16T nozzle were designed in the early 1950's and, for the most part, were calculated by hand. In addition, corrections have been made to the contours through the use of an influence coefficient correction technique in an attempt to remove small flow irregularities. This correction technique is not based on aerodynamic theory, and, as a result the corrected contours are not necessarily aerodynamically correct. A second problem stems from the fact that the application of the nozzle corrections results in nozzle contours that do not change in a monotonic manner. There are some ...


Laminar And Turbulent Natural Convection Heat Transfer In Trombe Wall Channels, Tony D. T. Chen Jul 1992

Laminar And Turbulent Natural Convection Heat Transfer In Trombe Wall Channels, Tony D. T. Chen

Mechanical & Aerospace Engineering Theses & Dissertations

The natural convective heat transfer and air movement in a Trombe wall solar passive system has been studied analytically and numerically. Three Trombe wall channel geometries including the parallel channel with axial inlet and exit, parallel channel with side vents and Trombe wall channel coupled to the room have been considered. Several models representing these Trombe wall geometries have been formulated. For the parallel channel with axial inlet and exit geometry, a momentum-integral method has been used to solve parabolic governing equations for two-dimensional laminar flow. This formulation leads to a second order ordinary differential equation for pressure defect in ...


Runge-Kutta Upwind Multigrid Multi-Block Three-Dimensional Thin Layer Navier-Stokes Solver, Frank E. Cannizzaro Jul 1992

Runge-Kutta Upwind Multigrid Multi-Block Three-Dimensional Thin Layer Navier-Stokes Solver, Frank E. Cannizzaro

Mechanical & Aerospace Engineering Theses & Dissertations

A state-of-the-art computer code has been developed that incorporates a modified Runge-Kutta time integration scheme, Upwind numerical techniques, Multigrid acceleration, and Multi-block capabilities (RUMM). A three-dimensional thin-layer formulation of the Navier-Stokes equations is employed. For turbulent flow cases, the Baldwin-Lomax algebraic turbulence model is used. Two different upwind techniques are available, van Leer's flux-vector splitting and Roe's flux-difference splitting. Full approximation multigrid plus implicit residual and corrector smoothing were implemented to enhance the rate of convergence. Multi-block capabilities were developed to provide geometric flexibility. This feature allows the developed computer code to accommodate any grid topology or grid ...


Development Of Prediction Technique For The Geometry Of The Abrasive Waterjet Generated Kerf, Yichung Chung May 1992

Development Of Prediction Technique For The Geometry Of The Abrasive Waterjet Generated Kerf, Yichung Chung

Dissertations

This study is concerned with the development of a practical and accurate technique for off-line determination of the variables characterizing the macro-geometry of the kerf generated in the course of abrasive waterjet (AWJ) machining of ductile materials. The study involved generation and processing of a database relating operational conditions with kerf dimensions. The total number of generated samples exceeded 1500.

A physical model relating the process results with operational conditions was constructed and used for the selection of a statistical technique for analysis of the acquired experimental information. The semiempirical model developed here is based on a simple theoretical model ...


Investigation Of Waterjet-Workpiece Interaction, Hung-Yuan Li May 1992

Investigation Of Waterjet-Workpiece Interaction, Hung-Yuan Li

Dissertations

The objective of this research is to develop new knowledge related to the fundamental physical phenomena of waterjet machining of ductile materials, and to use this knowledge to construct a numerical analysis model. The resulting knowledge will enable enhancement of waterjet cutting efficiency.

Experimental study of fundamental mechanisms and the acquisition of the data detailing micro and macro scale phenomena which occur during the machining process is carried out. It is shown that the material damage mechanism associated with waterjet machining is erosion cavitation which initiates ultrasonic stress wave propagation in the workpiece. Fatigue, an important element in producing material ...


Structural Reliability Using Finite Element Method, Che-Chen Liou May 1992

Structural Reliability Using Finite Element Method, Che-Chen Liou

Dissertations

During the last decade, structural reliability theory has been treated in a large number of research papers; therefore, from being a subject only well known by a relatively small number of researchers, it has become an important engineering discipline. From the application point of view, many practical applications have been made successfully.

In this dissertation some important fundamental concepts in statistics and in reliability theory are presented. The concept of failure mode can be defined as: A set of failed elements turn a structure into a mechanism. Usually, a structure has many possible failure modes; therefore, it will be necessary ...


Particle Dynamics Modeling Of Boundary Effects In Granular Couette Flow, Hyeong-Jin Kim May 1992

Particle Dynamics Modeling Of Boundary Effects In Granular Couette Flow, Hyeong-Jin Kim

Dissertations

This study provides insights in understanding boundary effects on the flow of dry granular materials composed of identical, smooth, inelastic spheres between parallel, bumpy walls in the absence of gravity. The results of this study are useful in providing a basis upon which developing theories can be modified as well as substantiating previous and current experiments. This in turn has a major importance in many industries which are concerned with handling of particulates, such as coal, mineral processing, powder metallurgy, and agriculture.

The particle dynamics or discrete element method is used to model this flow, thereby providing a means of ...


The Indentation Of Foam Pattern Surfaces By Coordinate Measuring Machine Probes, Nenawati Apr 1992

The Indentation Of Foam Pattern Surfaces By Coordinate Measuring Machine Probes, Nenawati

Master's Theses

When coordinate measuring machines are used to measure the complex shapes of foam patterns, the spherical probe tips indent into the soft surface of the pattern. Such indentation represents a measurement error since the indicated dimension will not be the same as the actual dimension. To determine the magnitude of error, the depth of probe tip indentation into PMMA and EPS foam surface (i.e., elastic indentation) was measured as a function of time, applied load, and foam density. The residual indentation after the removal of the load (i.e., plastic indentation) was also studied.

The depth of elastic indentation ...


Computational Simulation Of Flow Through Elbows In The Approach Piping Systems To A Headbox, Ramanathan Apr 1992

Computational Simulation Of Flow Through Elbows In The Approach Piping Systems To A Headbox, Ramanathan

Master's Theses

The successful operation of the wet end in a paper machine is highly dependent on the approach piping system. Sheet basis weight stability and ease of making wet end adjustments are greatly impaired by improperly designed approach piping systems. Most problems in headbox approach piping occur when the flow splits, combines, and passes through elbows.

Elbows create cross flows, flow separation, and eddies, and play an important role in the uniform and stable delivery of the pulp into the headbox. The effect due to an elbow lasts for a considerable distance downstream of the elbow and is severe when two ...


Shape Sensitivity Analysis And Optimization Of Skeletal Structures And Geometrically Nonlinear Solids, Ching-Hung Chuang Apr 1992

Shape Sensitivity Analysis And Optimization Of Skeletal Structures And Geometrically Nonlinear Solids, Ching-Hung Chuang

Mechanical & Aerospace Engineering Theses & Dissertations

Formulations and computational schemes for shape design sensitivity analysis and optimization have been developed for both skeletal structures and geometrically nonlinear elastic solids. The continuum approach, which is based on the weak variational form of the governing differential equation and the concept of the material derivative, plays a central role in such a development.

In the first part of this work, the eigenvalue and eigenvector sensitivity equations for skeletal structures are derived with respect to configuration variables of joint and support locations. This derivation is done by the domain method as well as the boundary method. The discrete approach for ...


A Computational Aerodynamic Design Optimization Method Using Sensitivity Analysis, Mohamed E. Eleshaky Apr 1992

A Computational Aerodynamic Design Optimization Method Using Sensitivity Analysis, Mohamed E. Eleshaky

Mechanical & Aerospace Engineering Theses & Dissertations

A new and efficient procedure for aerodynamic shape optimization is presented. The salient lineaments of this procedure are: (1) using a discrete sensitivity analysis approach to determine analytically the aerodynamic sensitivity coefficients; (2) obtaining the flowfield solution either by a computational fluid dynamics (CFD) analysis or, alternatively, by a flowfield extrapolation method which is based on a truncated Taylor's series; (3) defining the aerodynamic shape in such a way that it is not restricted to any class of surfaces and the optimizer automatically shapes the aerodynamic configuration to any arbitrary geometry; and (4) requiring no expertise other than that ...


Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin Apr 1992

Control Of Low-Speed Turbulent Separated Flow Over A Backward-Facing Ramp, John C. Lin

Mechanical & Aerospace Engineering Theses & Dissertations

The relative performance and flow phenomena associated with several devices for controlling turbulent separated flow were investigated at low speeds. Relative performance of the devices was examined for flow over a curved, backward-facing ramp in a wind tunnel, and the flow phenomena were examined in a water tunnel using dye-flow visualization. Surface static pressure measurements and oil-flow visualization results from the wind tunnel tests indicated that transverse grooves, longitudinal grooves, submerged vortex generators, vortex generator jets (VGJ’s), Viets’ fluidic flappers, elongated arches +a + a (positive angle of attack), and large-eddy breakup devices (LEBU’s) +a + a placed near the ...


Unsteady Euler And Navier-Stokes Computations Around Oscillating Delta Wing Including Dynamics, Ahmed Abd-El-Bar Ahmed Salman Apr 1992

Unsteady Euler And Navier-Stokes Computations Around Oscillating Delta Wing Including Dynamics, Ahmed Abd-El-Bar Ahmed Salman

Mechanical & Aerospace Engineering Theses & Dissertations

Unsteady flows around rigid or flexible delta wings with and without oscillating leading-edge flaps are considered. These unsteady flow problems are categorized under two classes of problems. In the first class, the wing motion is prescribed a priori and in the second class, the wing motion is obtained as a part of the solution. The formulation of the first class includes either the unsteady Euler or unsteady Navier-Stokes equations for the fluid dynamics and the unsteady linearized Navier-displacement (ND) equations for the grid deformation.

The problem of unsteady transonic flow past a bicircular-arc airfoil undergoing prescribed thickening-thinning oscillation is studied ...


Improving The Throughput Of Plasticating Extruders : Manufacture Of Non-Circular Pellets, Measurement Of Their Interparticulate Friction Coefficient, And Implications For Screw Design, Chia-Ying Liu Jan 1992

Improving The Throughput Of Plasticating Extruders : Manufacture Of Non-Circular Pellets, Measurement Of Their Interparticulate Friction Coefficient, And Implications For Screw Design, Chia-Ying Liu

Dissertations

This dissertation addresses the hypothesis that the interparticulate friction coefficient of a bed of polymeric particulates is a function of the cross-section of the pellets. Most pellets have a circular cross-section especially those that are strand cut. But when such pellets constitute a particulate bed there are few restrictions to adjacent pellets turning with respect to each other, or of the beds rupturing under shear load. This rupture can occur in plasticating extrusion, and it results in a poorly mixed melt with an inhomogeneous temperature distribution. The temperature fluctuations cause viscosity fluctuations which in turn cause pressure fluctuations. The pressure ...


Use Of The Conventional And Tangent Derivative Boundary Integral Equations For The Solution Of Problems In Linear Elasticity , Karim Heinz Muci Küchler Jan 1992

Use Of The Conventional And Tangent Derivative Boundary Integral Equations For The Solution Of Problems In Linear Elasticity , Karim Heinz Muci Küchler

Retrospective Theses and Dissertations

Regularized forms of the traction and tangent derivative boundary integral equations of elasticity are derived for the case of closed regions. The hypersingular and strongly singular integrals of the displacement gradient representation are regularized independently, through identities of the fundamental solution and its various derivatives, before the boundary integral equations are formed. Besides the displacements and the tractions, only the tangential derivatives of the displacements evaluated at the singular point appear in the regularized equations making them well suited for numerical treatment. The regularization of the hypersingular integrals demands that the displacement components have Holder continuous first derivatives at the ...


A Dynamically Adaptive Mesh Method For Internal Flows , John William Slater Jan 1992

A Dynamically Adaptive Mesh Method For Internal Flows , John William Slater

Retrospective Theses and Dissertations

A dynamic solution adaptive mesh method was implemented into a finite-volume numerical method for solving unsteady flowfields described by the two-dimensional, unsteady, Navier-Stokes and Euler equations. The objective was to improve the resolution and accuracy of solutions which contained flow gradients which varied in strength and position with time. Variational principles were used to formulate the mesh equations with which meshes were generated to have the desired smoothness, orthogonality, and volume adaption qualities. The adaption of the mesh to the flow solution was driven by the presence of flow gradients. The dynamics of the mesh was accounted for in the ...


An Interactive Graphical Approach To Off-Line Programming, James J. Troy Jan 1992

An Interactive Graphical Approach To Off-Line Programming, James J. Troy

Retrospective Theses and Dissertations

No abstract provided.


Effects Of Stinger Axial Dynamics And Mass Compensation Methods On Experimental Modal Analysis , Ximing Hu Jan 1992

Effects Of Stinger Axial Dynamics And Mass Compensation Methods On Experimental Modal Analysis , Ximing Hu

Retrospective Theses and Dissertations

A longitudinal bar model that includes both stinger elastic and inertia properties is used to analyse the stinger's axial dynamics as well as the mass compensation that is required to obtain accurate input forces when a stinger is installed between the excitation source, force transducer, and the structure under test. Stinger motion transmissibility and force transmissibility, axial resonance and excitation energy transfer problems are discussed in detail;Stinger mass compensation problems occur when the force transducer is mounted on the exciter end of the stinger. These problems are investigated theoretically, numerically, and experimentally. It is found that the measured ...


Thermal Analysis And Modeling Of A Precision Snap-Action Switch , Nien-Tsung Hsiao Jan 1992

Thermal Analysis And Modeling Of A Precision Snap-Action Switch , Nien-Tsung Hsiao

Retrospective Theses and Dissertations

The thermal performance of a V7 (the trade-name for a particular type of switch) precision switch was experimentally investigated and a computer model that predicts the heat transfer behavior was developed. The mathematical model of the switch, which is composed of a set of partial differential equations, is derived from the conservation law of energy, Fourier's law, and Newton's law of cooling. By using a numerical finite difference method, the resulting mathematical model is solved. The results show that this model predicts the temperature distribution of the switch reasonably well, especially the temperature rise of the terminal, which ...


Determination Of Secondary Sources In Noise Cancellation With Boundary Element Method , Guang-Hann Chen Jan 1992

Determination Of Secondary Sources In Noise Cancellation With Boundary Element Method , Guang-Hann Chen

Retrospective Theses and Dissertations

The direct boundary element method is proposed in this thesis to solve acoustic radiation problems as well as to achieve regional noise cancellation in half space with uniform finite impedance over the surface. The boundary integral equation and half space Green's function were derived to accomplish these goals. Those formulations were verified by comparing numerical simulations with theoretical solutions as well as experimental results. In addition, the above formulations were extended to achieve regional noise cancellation in half space by applying the boundary element method;Two methods were investigated to obtain noise cancellation in desired regions. They are the ...


Solution Of Viscous Flow Problems By Using The Boundary Element Method , Abdel-Magid Abdel-Latif Abdalla Jan 1992

Solution Of Viscous Flow Problems By Using The Boundary Element Method , Abdel-Magid Abdel-Latif Abdalla

Retrospective Theses and Dissertations

A scheme based on the Boundary Element Method (BEM) for solving the problem of steady flow of an incompressible viscous fluid is presented in this thesis. The problem is governed by both Navier-Stokes (N-S) equations and the continuity equation. The fundamental solution of the two-dimensional N-S is derived, and the partial differential equations are converted to an integral equation;The computer code is flexible enough to handle a variety of boundary and domain elements with different degrees of interpolation polynomial. Boundary and domain integrals over corresponding elements are evaluated analytically. The Newton Raphson iteration scheme accompanied by a relaxation factor ...


The Influence Of High Voltage Discharge On Flat Plate Drag At Low Reynolds Number Air Flow, Frans Soetomo Jan 1992

The Influence Of High Voltage Discharge On Flat Plate Drag At Low Reynolds Number Air Flow, Frans Soetomo

Retrospective Theses and Dissertations

No abstract provided.


An Artificial Neutral Network Fault-Diagnostic Adviser For A Nuclear Power Plant With Error Prediction, Keehoon Kim Jan 1992

An Artificial Neutral Network Fault-Diagnostic Adviser For A Nuclear Power Plant With Error Prediction, Keehoon Kim

Retrospective Theses and Dissertations

Since the accidents at the Three-Mile Island (TMI) and m Chernobyl nuclear power plants (NPPs), the safety of NPPs has become an even more important concern to both the nuclear power industry and the general public. The demand for safer plants has ever since. Responding to the demand, many scientists increased have investigated augmenting NPP safety in various ways. For m example, innovative reactor designs, better safety system R designs, human factor studies, stricter safety regulations, and so on, have been developed and implemented in the years since the above-mentioned accidents.


Study Of Beamforming Techniques For Ultrasound Imaging In Nondestructive Testing , Sleiman Riad Ghorayeb Jan 1992

Study Of Beamforming Techniques For Ultrasound Imaging In Nondestructive Testing , Sleiman Riad Ghorayeb

Retrospective Theses and Dissertations

Many of the innovations in modern materials testing technology make use of ultrasound. Therefore, the theory and application of ultrasound have become of extreme importance in nondestructive inspection of complete engineered systems. However, despite the fact that most of these ultrasound inspection techniques are based on well-established phenomena, two key problems pertaining to their application still remain unresolved. These problems can be identified as (1) the material being tested is assumed to be isotropic and homogeneous by nature, and (2) the scanning/data collection process, prior to the reconstruction scheme, is very time consuming. As a result, techniques for fast ...