Engineering Commons^™

A Thermal Contact Conductance Correlation For Mechanically Expanded Finned Tube Heat Exchangers, Mahmoud Ahmed Abu Ebid

Masters Theses

"Tests were conducted in dry vacuum environment, on eight mechanically expanded finned tube heat exchangers (with 3/8 inch outer diameter tubes) with different geometries including variation in fin thickness, fin collar length, and net interference. One of the eight heat exchangers was also tested under wet conditions. A mathematical model was used to calculate the thermal contact conductance from the experimental data. An error analysis was performed to estimate the range of error in determining the thermal contact conductance. A correlation of the dry contact conductance in terms of fin number (actual fin collar length in contact with the tubes), …

Electronic Ballast Having Emitter Coupled Transistors And Bias Circuit Between Secondary Winding And The Emitters, Don Cronin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An electronic ballast for energizing fluorescent lamps comprising a converter including a rectifier and a filter for converting an alternating source voltage into a direct current voltage, a network including first and second switching transistors, a tank circuit having a primary winding of a transformer, a secondary winding of the transformer for providing feedback of a portion of the voltage developed across the tank circuits and a bias circuit coupled between the opposite ends of the secondary winding and the emitters of the transistor for alternatively applying bias to the transistors, the network serving to convert a direct current voltage …

An Analytical Design Procedure For The Determination Of Effective Leading Edge Extensions On Thick Delta Wings, Farhad Ghaffari

Mechanical & Aerospace Engineering Theses & Dissertations

An analyt1cal des1gn procedure for Lead1ng-Edge Extensions (LEE) has been developed for thick delta wings. This LFE device is des1gned to be mounted to a w1ng along the pseudo-stagnation stream surface associated w1th the attached flow design lift coeff1cient of greater than zero. The intended purpose of the device is to improve the aerodynamic performance of high subsonic and low super son1c aircraft at incidences above that of attached flow design lift coefficient, by us1ng a vortex system emanating along the leading edges of the device. The low pressure assoc1ated with these vort1ces would act on the LEE upper surface …

Underwater Acoustic Wavefront Phase Fluctuations, George L. Vojtech Jr.

OES Theses and Dissertations

In conventional underwater acoustics sound propagation is generally modeled and applied as a coherent or incoherent process. This paper addresses a relatively new theory, that of a range driven increasingly incoherent ray propagation through a real ocean environment, Possible mechanisms are discussed and experimental data presented to reinforce the theory.

Applications Of Finite And Wave Envelope Element Approximations To Acoustic Radiation From Turbofan Engine Inlets In Flight, A. V. Parrett

Doctoral Dissertations

"The problem of acoustic radiation from turbofan engine inlets in flow has not lent itself fully to analysis by numerical means because of the large domains and high frequencies involved. This project has extended the use of finite elements and wave envelope elements, elements which simulate decay and wavelike behaviour in their interpolation functions, from the no-flow case in which they have been proven, to cases incorporating mean flow. By employing an irrotational mean flow assumption, the acoustics problem has been posed in an axisymmetric formulation in terms of acoustic velocity potential, thus minimising computer solution storage requirements. The wave …

Modeling Of Purge Valve Closure, William W. Durgin, Benito Zannini

Office of the Provost Scholarship

In some nuclear reactor containment isolation applications, butterfly valves with pneumatic actuators are used to close pipelines in the event of containment pressure transients resulting from postulated accidents. A model is developed which predicts the closure time history of such valve/actuator systems under prescribed transients. Examples are presented which show the importance of the valve and actuator characteristics. It was found that actuation delays of sufficient magnitude could allow the dynamic torque to exceed the available actuator torque, thus preventing valve closure.

Sun Position In Florida, Florida Solar Energy Center, Ross Mccluney

FSEC Energy Research Center®

Described herein is a procedure for determining the path of the sun through the Florida sky relative to a solar collector array, a window, a skylight or an entire building - information needed by architects, engineers and others for shading and orientation calculations involved in active and passive building design. It can be used for positioning exterior shading devices for maximum benefit. This information can also be used to pinpoint solar collector shading problems.

Open-Cycle Ocean Thermal Energy Conversion, Florida Solar Energy Center, Magdy Girgis

FSEC Energy Research Center®

In May 1983 the Florida Solar Energy Center(FSEC) received $ 328,000 from the federal Solar Energy Research Institute in Colorado to determine the feasibility of an Open-Cycle Ocean Thermal Energy Conversion (OTEC) concept. The objective of the project is to assess the economic and technological viability of the conceptual design of an Open Cycle OTEC power plant. FSEC and Create R&D Inc., Hanover, New Hampshire, bring together complementary skills and experience in resource assessment, component design, system engineering and project management. FSEC also will study possible sites for an OTEC plant in Florida as part of a complementary project funded …

Augmentation Of Free Surface Heat And Mass Transfer Due To Electrostatic Fields, Alan F. Smelewicz, Mark P. Majcher, James B. Nystrom, William W. Durgin

Office of the Provost Scholarship

Experiments were conducted to measure heat transfer rates and mass transfer rates from a water surface in the presence of electrostatic fields of various strengths generated between the water surface and a wire grid above the surface.

Heat transfer rates were determined by the temperature decay after heating the test and control basins. Mass transfer rates were determined by measuring the water loss while holding the basins at fixed temperatures.

It was found that very little increase in transfer coefficients took place for voltages below an onset voltage which depended on atmospheric conditions and test geometry. The heat transfer coefficient …

Photovoltaics: A Question And Answer Primer, Florida Solar Energy Center, Ingrid Melody

FSEC Energy Research Center®

Of all the solar energy technologies, photovoltaics (PV) show the greatest promise for worldwide acceptance and application. Their universal appeal lies in the fact that they generate electricity from the sun. Working photovoltaics have no moving parts, are relatively simple in design, need very little maintenance and are environmentally benign. They simply and silently produce electricity whenever they are exposed to light.

Passive Cooling Ideas For The Southeast, Florida Solar Energy Center, Chris Beck

FSEC Energy Research Center®

A passively cooled home is one which is kept relatively comfortable through natural means. Homeowners in the Southeast have been using passive building techniques in order to live more comfortably during hot, humid seasons since the early 1900's. The concept of designing for minimum use of artificial cooling and heating systems is not new, but with the advent of sophisticated mechanical air-conditioning and heating systems and the availability of inexpensive fossil fuels in the '40s and '50s, builders began bypassing passive techniques. Too many of today's homes are designed with more concern about accommodating a mechanical conditioning system than with …

An Interactive Procedure For Numerical Design Optimization, Jaehwan Lee

Theses

An interactive version of the numerical design optimization method of Pappas for the solution of nonlinear optimization problems is presented in this thesis, A designer intervention strategy is employed herein for interactive optimization to allow the designer to control and manage the optimization process. This procedure embodied in the interactive CADOP6 program is tested on the ten bench mark problems of Eason and Fenton to illustrate the designer intervented optimization process and to provide a comparison with the fully automated procedure of Pappas This designer intervented interactive program appears more effective and faster than the completely automated CADOP5 code on …

Measurement Of Thermal Conductivity Of Polymers Using Line Source Method, Manojkumar C. Patel

Theses

The purpose of this investigation was to evaluate the Line Source technique to measure the thermal conductivity of different molten polymers. Although the results obtained using this method are within acceptable experimental error limits, due to tec reasons explained, the results are not as accurate as claimed in the literature which describe this technique.

High Speed Puncture Impact Studies Of Structural Foam Plaques, Shashi B. Kumar

Theses

The constant velocity high speed impact study was conducted on different thermoplastic and thermoset structural foam plaques to study their impact behavior. Plaques of Noryl, Polycarbonate, Polystyrene and Polyurethane were carefully chosen to represent a true sample of the manufactured product. Test plaques were marked such that specimens could be tested for variation in location, thickness of the plaque and variation between plaques. High speed puncture impact experiment was conducted on each specimen and the results were analysed.

The test results showed that the impact performance varied significantly over the plaque. Noryl and Polycarbonate did not exhibit any correlation for …

Experiments On Melting Around An Isothermal Horizontal Cylinder Under Computer Control, Timothy Moore Rothgeb

Mechanical & Aerospace Engineering Theses & Dissertations

The melting of a solid around an isothermal horizontal cylinder is a physical phenomenon which must be understood when attempting to design a latent heat storage system. The desire to design such a system is the motivating factor in this research. To gain this understanding of the fundamental melting processes several experiments were designed, and two sets of Stefan and Rayleigh number experiments were undertaken. Experiments were also performed to determine the properties of the paraffin that was used in these investigations. During the investigations of the melting processes, the temperature was measured at several locations throughout the liquid and …

An Experimental Investigation Of Round Normal Impinging Jet Of Water, Dipendra Saharay

Theses

The various flow parameters of round jets of water impinging normally on a flat plate are measured experimentally. The velocity and pressure distribution along the axis of the jet at various sections of the jet parallel to the horizontal lucite striking plate and along the impinging surface was found. The nozzles used were 1/4 inch and 1/2 inch in diameter. The Reynolds number based on the nozzle diameter was 15,000 to 25,000. The distance from the jet origin to the deflecting boundary ranged from thrice the diameter of the jet to twelve and sixteen times the diameter of the jet. …

The Quasisteady Approach For Thermal Analysis Of Frost Action Below Refrigerated Warehouses, Milan Kumar Bag

Theses

The quasisteady method of analysis has been used to determine the frost depth below refrigerated warehouses. For the case when the ground temperature is different from phase change temperature, the solution is obtained by numerical integration of the equation governing the phase change process. When the ground temperature approaches the phase change temperature closed form solution is obtained. The results obtained from the quasisteady method compare well with the experimental results. The results presented in this thesis should find use in the design of the refrigerated warehouses in the colder regions of the world.

Experimental Investigation Of An Axisymmetric Air Jet Impinging On A Flat Plate, Saibal Basu

Theses

Experimental investigation was carried out on a circular, submerged, axisymmetric turbulent air jet-with normal impingement on a smooth, flat, square lucite plate, The flow was considered to be incompressible because the velocity of the jet was not too high, with Mach Number of the order of 0.3. Three nozzle diameters of 0.375" (9,525 mm), 0.250" (6.35 mm) and 0.125" (3.175 mm) were used with Reynolds number ranging from 7,000 to 70,000.

Various flow parameters were measured to obtain the velocity and pressure distributions at the surface of the flat lucite plate and along the centerline of the normal impinging air …

Deposition Of Particles In Horozontal Parallel Plate Channel Due To Image Charge, Inertia, Viscosity And Gravity, Chi-Young Chu

Theses

This investigation was made to determine the effect on the deposition of particle in a horizontal parallel-plate channel due to the influences of image charge, viscosity, inertia and gravity. The flow considered was lamina, incompressible and steady. The flow patterns considered were uniform and fully developed with symmetry about the axis of the channel.

The governing equations derived for a particle were based on Newton's Second Law of motion. Since the resulting governing equations are linear second order differential equations, Runge-Kutta algorithm is used to solve the problem and graphical techniques is used to interpret the results of the numerical …

Domestic Water Heating With Microwave Radiation, Dan Lynn Merchant

Graduate Research Papers

Purpose of the Study

1. To determine if microwave radiation can be safely employed in a domestic water heating system.

2. To determine if microwave radiation can be efficiently and economically employed in a domestic water heating system.

3. To determine if microwave radiation can be effectively employed in a domestic water heating system.

Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Toupin's version of the Saint-Venant principle in linear elasticity is generalized to the case of linear elasticity with microstructure. That is, it is shown that, for a straight prismatic bar made of an isotropic linear elastic material with microstructure and loaded by a self-equilibrated force system at one end only, the strain energy stored in the portion of the bar which is beyond a distance s from the loaded end decreases exponentially with the distance s. © 1983 Martinus Nijhoff Publishers.

The Relative Importance Of Competencies Needed By Industrial Energy Managers From The Larger Manufacturers In Iowa, Timothy J. Eibes

Graduate Research Papers

The importance of identifying the competencies needed by energy managers is reflected in the seriousness of the energy problem and the impact it has on the industrial setting. The newness and ambiguity of EM, coupled with the increasing importance of the concept, add to the need for identifying the necessary competencies required in managing energy.

Ideally, once these competencies are identified, they should be the focus of those educational curriculums designed to produce energy managers. Currently there are only 25 post-high school institutions in the U.S. that have energy management curriculums (The College Blue Book, 1981). Less than half of …

Entry-Level Computer Aided Design And Drafting Skills, Stephen D. Rockey

Graduate Research Papers

The purposes of the study were to:

1) determine the entry-level competencies necessary for CAD system operation, and

2) rank in order of importance the competencies identified to be necessary for entry-level CAD system operators.

Designing And Installing Commercial Solar Pool Heating Systems, Florida Solar Energy Center, Douglass E. Root

FSEC Energy Research Center®

Solar heating of swimming pools is an economically attractive utilization of Florida's abundant solar resource. The temperature requirement is lower than that of domestic or service water heating, lower than that for building heating and far lower than that for solar powered air conditioning. Florida's year-round mild and sunny climate allows swimming during much of the winter, so a properly heated pool is economically attractive.

Finite Element Analysis Of The Femoral Head, Ghandikota Ramamurthy

Theses

Femoral component loosening and Prosthetic stem fractures have renewed interest in conservative alternatives to conventional total hip replacements. One such alternative is the concept of surface replacement. The objective in this study is a finite element analysis of a femoral surface replacement cup with Particular attention given to the interfacial stresses. An axisymmetric model with a grid of two-dimensional isoparametric elements is generated. This study utilizes an adaptive model so as to include the effect of bone remodeling in response to stress. The stiffness is considered to be linearly proportional to the stress in the femoral head and neck. Isotropic …

Simulation Of Rotational Molding, Hersel Ahdout

Theses

A computer program is written in FORTRAN IV to simulate the Rotational Molding process based on the discrete technique suggested by Progelhof and Throne. This program employs three techniques of Finite Difference, Euler's, Crank Nicolson's, and pure implicit, with their inherent accuracy and cost limits. The program has the capability of updating the variable parameters of polymer as the temperature rises, which eventuall leads to the closest simulation possible to the actual experiment.

Accuracy And Convergence Of Finite Element Approximations, Gwo-Tar Chang

Theses

In the design of structure, the engineer seeks to determine the distribution of stresses throughout the structure or the displacements at certain points of the structure. The finite element method is a numerical analysis technique for obtaining approximate solutions to engineering problems that are not amenable to closed form solutions.

In this work the triangular element and the rectangular element in plane stress are employed in the development of the formulation of element stiffness equations. The effect of the number of elements on the convergence to the analytical solution was investigated. Similar study using rectangular elements was also carried out …

Computer Simulation Of Cavity Filling During Injection Molding Process, Sumit Banerjee

Theses

A numerical technique is proposed for the simulation of cavity filling process during injection molding of glass-bead filled polypropylene. The mold cavity is of cylindrical shape. Marker And Cell (MAC) method is utilized for solving the transient flow phenomena, after a mathematical simulation of the flow model is carried out by using the relevant continuity and-momentum equations governing the system. The complexity of the equations involved, results in the simplifying assumption of incompressible and isothermal flow process. A computer program is written on the basis of finite-difference equations developed during the application of MAC method under the prevailing conditions.

The …

One-Dimensional Compressible Flow Analysis : Isentropic And Normal Shock, Su-Bo Wong

Theses

A computer program to compute and analyse one-dimensional isentropic compressible flow through variable cross-sectional area with or without a normal shock is developed. The program is written in the "FORTRAN LANGUAGE".

In this work, the area change is the predominant cause of change of flow condition. One of the advantage of this program is set on general uses for isentropic flow. In common practice, the values of the isentropic flow property ratios were tabulated or graphically presented as function of the Mach number with a specified specific heat ratio, K (normally K=1.40 was presented). With todays technology, the most versatile …

A Finite Difference Solution Of An Ideal, Normal, Impinging Jet, Luis A. Gast

Theses

The free boundary of a circular jet of an irrotational, inviscid, incompressible, fluid impinging normally to a flat surface from a height of 2 times the nozzle radius, was found by a finite difference method.

Starting with a graphical solution, approximate values of the potential were given to the nodes at the field.

Having the equipotential lines perpendicular to the axis of the jet, perpendicular to the impinging surface, and having defined the value of the potential at both the entrance and exit of the jet, a finite difference expression of the Laplace's equation was used in an iteration scheme …