Mechanical Engineering Commons^™

Determination Of Thermal Contact Resistance Between Metals Using A Pulse Technique, William Edward Stewart Jr.

Doctoral Dissertations

"This dissertation reports the results of an experimental and analytical investigation to determine the thermal contact resistance of several metal specimen pairs using a relatively new pulse technique. Metal specimens were aluminum 2024-T3, aluminum 6061-T6, aluminum 7075-T6, copper 110, stainless steel 304, molybdenum, and Armco iron. Thermal contact resistance was also determined for dissimilar metal specimen pairs of aluminum 6061-T6 - copper 110 and aluminum 7075-T6 - copper 110. Aluminum 7075-T6, copper 110, and stainless steel 304 specimens were tested to determine the variance of contact resistance with time after loading.

Specimens were circular cylindrical disks between .033 and .061 …

An Experimental Investigation Of The Effects Of Ambient And Heated Steady Flow And Intense Sound Levels On The Response Of Acoustic Filter Elements, Raymond H. Schaffart

Doctoral Dissertations

"The primary purpose of this research was to investigate the effects of flow and finite amplitude waves on the response of acoustic elements. A further purpose was to evaluate the effects of elevated temperatures and cross-sectional dimensions on element performance. As an integral part of this work various laboratory techniques were explored for their suitability.

Empirical models for the acoustic impedance of side branch resonators were developed for the two operational modes, i.e., flow past the resonator and finite amplitude wave inputs. A description of the complex variation of the acoustic resistance of the resonator with flow past and variable …

Combined Thermal Weakening And Mechanical Disintegration Of Hard Rock, George Bromley Clark, T. F. Lehnhoff, Gary F. Fenton, M. R. Patel, Jaw K. Wang, Vernon Dale Allen

Mining Engineering Faculty Research & Creative Works

This investigation of the combined effects of thermal weakening and mechanical disintegration (thermomechanical fragmentation) was initiated with a view toward better understanding of the processes required for more rapidly and economically fragmenting or excavating hard rock. Boring machines for utility tunnels, transportation tunnels or mining operations may be able to utilize the advantages of processes such as thermomechanical fragmentation. Secondary fragmentation or rock crushing processes also can conceivably employ the data obtained from this study.

Laminar Heat Transfer For Small Prandtl Number Fluids Including Step Change In Wall Temperature, Shiny Ting

Masters Theses

"The object of this investigation is to provide a simple means of determining the heat transfer from a flat plate which has an unheated leading length x₀. The case of steady, two-dimensional, laminar flow of an incompressible fluid with a Prandtl number of less than one is considered. Since there exists an unheated length and the Prandtl number of the fluid is less than one, the thermal boundary layer intersects the flow boundary layer. Thus, the solution of the problem divides into two regions. In this study, the problem is solved analytically by employing the energy integral equation. The temperature …

Report On The School Of Mechanical Engineering National Technical Center Saigon, South Vietnam, Myrne R. Riley

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

"Training in the discipline of Mechanical Engineering is offered in South Vietnam by the School of Mechanical Engineering, one of four engineering schools and a Merchant Marine School composing the National Technical Center located presently in the Phu Tho region of Saigon, South Vietnam. The school was established in 1956 for the training of engineers, for mechanical and industrial activities. It became part of the National Technical Center, established by Decree No. 213-Gd by the President of the Republic of Vietnam on June 29, 1957 and graduated the first class of 20 in the summer of 1960. The KS Degree, …

Floating Bubble Configurations, Robert A. Medrow, B. T. Chao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The configurations of bubbles floating at a vapor-liquid interface are investigated both analytically and experimentally. The differential equations governing the shape of a single bubble at rest in a liquid of infinite extent are deduced under the assumption of zero dome thickness, uniform surface tension, and equal gas densities within the bubble and above the interface. These equations show that nondimensional bubble shapes depend upon the value of a single parameter. An analytical solution, valid for small bubbles, is developed and shown to be in good agreement with the general numerical solution. Good agreement with theory is demonstrated for floating …

Heat Transfer From An Oscillating Horizontal Wire, Bassem F. Armaly, D. H. Madsen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The effect of vibration on heat transfer by natural convection has been investigated experimentally using a thin wire, 0.010 in. in diameter, and air as a convection medium. Horizontal reciprocating motion of varying amplitudes, peak-to-peak values of 0-2.655 in., and frequencies, 0-20 cps, was applied to an electrically heated horizontal wire. The average wire velocity (frequency times total path length traveled per cycle by the wire) was used to correlate and predict the experimental results. © 1971 by ASME.

Density Distribution Measurements In Rarefied Gases Contained Between Parallel Plates At High Temperature Differences, Darryl J. Alofs, Richard C. Flagan, George S. Springer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Density Distributions Were Experimentally Determined in Rarefied Gases at Rest Contained between Two Parallel Plates Maintained at Widely Different Temperatures. the Temperatures of the Hot and Cold Plates Were ∼79°K and ∼294°K, Respectively, Resulting in a Temperature Ratio of About 4:1. Both Helium and Nitrogen Were Used as Test Gases. Particular Attention Was Focused on Obtaining Data in the Temperature Jump and Transition Regimes. the Gas Densities Were Measured by Observing the Luminescence Produced by a High-Energy Electron Beam Traversed between the Plates. in Addition to the Density Measurements, Heat Transfer Measurements Were Also Made in Order to Estimate the …

The Axial Contact Of Finite Elastic Cylinders With Application To Thermal Contact Resistance, Ross Orlo Mcnary

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Predictions of the macroscopic thermal contact resistance have been severely restricted because the macroscopic contact area between finite members could not be determined. A new method of solution to this contact problem in elasticity is developed which is applicable to a wide variety of geometries and boundary conditions. A physical lumped-parameter model is employed from which the finite difference equations in terms of displacement are derived. Calculations using this method indicate that large errors in the prediction of the thermal contact resistance can result if solutions for bodies of infinite extent are employed for finite regions of interest. Especially large …

Charges On Jet Drops Produced By Bursting Bubbles, Robert A. Medrow, B. T. Chao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The sizes and charges of jet drops produced by bursting air bubbles are examined experimentally. The variation in charge for bubble lifetimes of up to 200 sec in NaCl and KCl solutions is reported. Jet drops refer to drops produced by a jet rising from a cavity left in a liquid surface by a bursting bubble; bubble lifetime is the interval during which a bubble is in motion between generation and rupture. With other variables held constant, drop charge shows a characteristic variation of a rise to a maximum followed by a decrease to an asymptotic value, as bubble lifetime …

The Influence Of Member Length On Thermal Contact Resistance In A Vacuum Environment, Larry Martin Cooper

Masters Theses

"An investigation was conducted to determine the influence of member length on thermal contact resistance in a vacuum environment. A model was created which consisted of a center rod axially loaded between two other members. It was assumed that circular macroscopic constriction areas were formed at the contact interface when the rods were loaded. Macroscopic modeling of the contact surfaces makes the thermal contact analysis a function of the mechanical and thermal boundary conditions of the total body. The method of finite differences was employed to calculate the temperature distribution, heat flows, and thermal contact resistance of each member. Data …

Design And Preliminary Testing Of A Thermomechanical Rock Fragmentation Apparatus, Gary Earl Fenton

Masters Theses

"The design characteristics of equipment to thermally weaken and mechanically fragment hard rock were developed and the apparatus constructed. An initial investigation of thermo-mechanical fragmentation was conducted on Missouri red granite. The particles from the fragmentation tests were sized and this analysis was used in the Rittinger theory to calculate surface area breakage energy. It was found that the application of thermal energy could reduce the surface area breakage energy per unit volume of material removed by as much as 41 percent. The use of kerfs in the rock increased the amount of material removed and permitted larger particles to …

A Study Of A Nitrogen Heat Pipe, Jay Dudheker

Masters Theses

"An experimental heat pipe, 33.25 inches long and 0.75 inches in diameter, with modacrylic fiber wick and liquid nitrogen as its working fluid was constructed to study the operating characteristics of a cryogenic heat pipe. The effective thermal conductivity and the axial temperature distribution were determined for various levels of power input. The effect of inclination angle on the above parameters was also measured"--Abstract, page ii.

A Triangular Element For Numerical Solutions Of Axisymmetric Conduction Problems In Cylindrical Coordinates, Prafulla Chandra Mahata

Masters Theses

"The triangular element is one of the many suitable elements which are used in finite difference methods as applied to conduction heat transfer. Such elements find many applications in conduction problems in Cartesian coordinates. This work proposes a new triangular element for axisymmetric conduction problems in cylindrical coordinates. The validity and workability of the networks formed by the proposed triangular elements are strengthened by selected examples. The work is completed by the application of the triangular element to an industrial problem having irregular boundaries. The results are compared with the solution obtained by the finite element method"--Abstract, page ii.

An Experimental Determination Of The Effect Of The Axisymmetric Turbulent Wake On The Pressure Distribution On A Sphere, Martin Gardner Bowin

Masters Theses

"A study of the effect of the turbulent wake of a water drop on the motion of a smaller droplet is essential in order to gain an understanding of the behavior associated with the collision coalescence phenomena. The use of spheres of macroscopic size proves to be a valuable method in observing these effects. This experimental investigation centers on (1) a check on the validity of the instrumented sphere as a device to measure normal static pressure, and (2) the study of the effect of the turbulent wake of the test model sphere upon the instrumented sphere. Measurements were made …

The Thermal Contact Resistance Of Lubricant Films In Vacuum, Garry A. Heizer

Masters Theses

"This paper presents the results of an experimental investigation on the thermal contact resistance of lubricant films and bare interfaces. The apparatus and procedure used in the determination of these resistances are described. Twelve series of tests were performed to evaluate the effects of temperature and contact pressure on the thermal resistance of lubricant films. Variations of thermal contact resistance with temperature and contact pressure for four lubricants and for bare interfaces are presented graphically. The thermal resistances of the four lubricants tested in vacuum conditions: lithium grease, graphite grease, molykote grease, and silicone lubricant, were found to lie in …

A Study Of Radiative Heat Transfer From A Spherical Layer, Hakimuddin Kalimuddin Khalil

Masters Theses

"The problem of radiative heat transfer from a spherical layer of absorbing-emitting gas has been studied. First, the medium is assumed to be gray and then nongray. A thorough survey of literature from fields other than heat transfer, such as astrophysics and neutron transport has been made to stimulate further interest in this important area. To gain some insight into the effect of various parameters on the heat transfer, simple physical situations involving isothermal medium are considered. Comparison of the results obtained for the flux from the spherical and planar layers reveal that the curvature becomes increasingly important as the …

Two Component Heat Pipe, Surapol Chandsawangbhuvana

Masters Theses

"A two component heat pipe with water and ethanol as the working fluid was investigated at different angles of inclination and various ethanol concentration for two power loads. The heat pipe was 15 inches long and 0.75 inches in diameter with a 100 mesh stainless steel screen wick. The wall and the vapor temperatures were measured at different stations along the length of the heat pipe by copper-constantan thermocouples. The results were used to evaluate an existing model which includes the constraint of thermodynamic phase equilibrium of the solution on the governing equations. Based on the measured pressure and temperature …

Radiant Interchange In A Non-Isothermal Rectangular Cavity, Tilak Raj Sawheny

Masters Theses

"Radiant interchange between non-isothermal, gray diffuse surfaces with non-uniform radiosity has been determined for a rectangular cavity. Temperature distribution and heat flux as thermal specifications for the parallel surfaces of the cavity have been considered separately. Ambarzumian's method has been used for the first time to solve a radiant interchange problem. According to the method, the integral equation for the radiosity is first transformed into an integro-differential equation and then into a system of ordinary differential equations. Initial conditions required to solve the differential equations are the H-functions. The H-functions represent the radiosity at the edge of the cavity for …

A Step-Wise Gray Approximation Of The Radiative Absorption Coefficient For An Isothermal Hydrogen Plasma, Keith Harlan Browne

Masters Theses

"The radiative absorption coefficient of an isothermal hydrogen plasma is calculated using a step-wise gray approximation. The approximation retains a high degree of accuracy while significantly reducing the numerical computer time. The accuracy of the approximation depends on the spacing of the steps taken in the frequency spectrum as well as the number or steps used; 135 steps are used in this study. Plasma conditions of interest in this study are for temperatures between 5000 and 60,000ºK, densities between 10⁻⁵ and 10⁻⁷ gm/cm³, and thicknesses between 0.1 and 100 cm. Flux and intensity calculations are made for each case using …

Feed Drive Design For Numerically Controlled Machine Tools, Subash Bhatia

Masters Theses

"The various types of feed drive control systems used in numerical control of machine tools have been broadly classified. Further a step by step design has been presented for the feed drive of a numerical contouring control milling machine. The aim has been to develop a consistent strategy for tackling a variety of such problems. Consequently stress has been laid on principles and not on design figures"--Abstract, page ii.

Design Of A Semi-Automatic Transmission, Yogendra Prahladray Buch

Masters Theses

"Design of a semi-automatic four-speed transmission for automotive engines with moderate horsepower is described. The basic configuration consists of main and countershafts and five pairs of constant-mesh gears. Engine torque is transmitted through an input gear pair to the countershaft, and finally to the output shaft through a selected output gear pair. Selection is accomplished by engaging one of five hydraulically operated clutches located on the countershaft. Engagement fixes the desired gear to the countershaft and engine torque is then transmitted to the mating gear, which is fixed to the output shaft. Fourth speed is obtained by coupling the input …

The Effect Of Diameter On The Film Boiling Behavior Of Liquid Nitrogen, William Joseph Wafer

Masters Theses

"A film boiling heat transfer study was conducted for liquid nitrogen at atmospheric pressure. The heat transfer surfaces used were cylinders with outside diameters of 0.450, 0.650, 0.850, and 1.000 inches. The temperature differences covered were from approximately 150ºF to approximately 600ºF. The data indicate that the heat flux will decrease to a minimum then increase slightly as the diameter of the heat transfer element is increased at constant temperature difference. The heat transfer coefficient is expected to approach a flat plate correlation as the diameter approaches infinity"--Abstract, page ii.

Laser Interferometric Holography Investigation Of Free Convection About A Vertical Plate Of Non-Uniform Temperature, Richard Kenneth Thomson

Masters Theses

"An experimental investigation was conducted using a holographic interferometer to detect the temperature variation in a free convection boundary layer about a vertical heated plate. The heated plate was non-isothermal and investigations were conducted for four temperature distributions; the maximum plate temperature ranged from 200F to 493F. Photographs were taken of the fringe patterns and boundary layer thickness measurements, as well as temperature measurements, were made. A theoretical model was constructed by applying the integral method to the energy and momentum equations. The experimental values agree quite well with this model. The advantages of the holographic interferometer over other systems …

An Investigation Of A Bistable Oscillator Used In A Phase Modulated Control Circuit, Yu-Fang Yen

Masters Theses

"A primary component in the investigation of phase modulated control systems is bistable oscillator which converts a constant oscillation signal to control the system. The oscillator is feedback type that utilizes a feedback capacitance and resistance in each feedback path to change its frequency. The theoretical behavior of bistable oscillator was investigated and the non-dimensional results were set for convenience in determining the oscillation period. The control circuit which based on the oscillator was also presented a form of suitable circuit for direct application to practical control problems"--Abstract, page ii.

Development Of An Elastic-Plastic Finite Element Program With The Initial Strain Approach, Vernon Dale Allen

Masters Theses

"A finite element method is presented for solution of plane stress and axisymmetric elastic-plastic problems employing the method of successive elastic solutions with the initial strain approach. The problem of nonconvergence of the initial strain approach for perfectly plastic problems was eliminated by expressing the Prandtl-Ruess equations entirely in terms of strain. Two examples are presented to demonstrate the validity of the method"--Abstract, page ii.

Cylindrical Couette Flow Experiments In The Transition Regime, Darryl J. Alofs, George S. Springer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Density Distributions Were Measured in Rarefied Argon Contained between Two Concentric Cylinders, the Inner One Rotating, the Outer One Stationary. the Experiments Were Performed with a Mach Number Near Unity, based on the Surface Speed and Surface Temperature of the Rotating Cylinder. Particular Attention Was Focused on Obtaining Data in the Slip and Transition Regimes Where the Knudsen Number, Defined as the Ratio of the Mean Free Path to the Gap Size between the Cylinders, Varied from 0.04 to 1.07. the Density Distributions Were Measured by Observing the Gas Luminescence Induced by the Passage of a Narrow Beam of High …

An Approximate Model For The Static Operation Of A Fluidic Amplifier Employing Axisymmetric Jets, Richard T. Johnson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approximate mathematical model for the static, no-load (blocked receiver) operation of a fluidic amplifier employing axisymmetric jets is developed. The amplifier is similar in concept to the three-terminal modulator developed by the Johnson Service Co. The approach used in developing the model assumes that the complex flow phenomena can be represented by the combination of several elementary flow problems. The model employs the concept of an equivalent power nozzle in describing downstream flow with a control signal present. Experimental results are presented to justify assumptions and evaluate parameters. © 1971 by ASME.

Identification Of Centers Of Influence For Urban Areas, Robert W. Meyer

Doctoral Dissertations

"A method is developed for the identification of the spatial locations about which urban population densities tend to be distributed. The identification of these "influence centers" is based upon the use of available census data. The method is developed for application to any population characteristic which can be logically represented in terms of spatial density. Examples of such characteristics are; total population, population by race, and population by income group. The method is empirically developed and verified for restricted spatial distributions using artifically generated census tract information. These spatial distributions are compatiable with population distributions that are most readily modeled …

An Investigation Of Subsequent Yield Phenomena, Joseph George Hoeg

Doctoral Dissertations

"A method utilizing high pressure fluid environments is described whereby a three-dimensional subsequent yield surface was determined for 304 stainless steel. Cylindrical parent specimens of this material were prestrained in axial compression under fluid pressure and then small sub-specimens were sectioned from these parent specimens. Finite element techniques were used to optimize the parent specimen size so that a zone of uniform axial stress would result during the prestraining. Longitudinal strains in this zone were monitored during the prestraining and the sub-specimens were cut from this region in a manner that did not allow the machining to appreciably affect the …