Mechanical Engineering Commons^™

Development Of Helicopter Flight Path Models Utilizing Modern Control Techniques, Alfred Fermelia

Doctoral Dissertations

"The nonlinear set of equations which represents helicopter motion are linearized about a prescribed nominal state. Once the linearized system is obtained it is validated by comparing the output of the nonlinear system to that of its linearized counterpart. Having obtained a linear model, linear system theory may then be applied in order to investigate the stability and control characteristics of the aircraft.

General techniques for simulating helicopter pilot response for inclusion in a flight path simulation program have been devised. To provide the desired flight goal, a nominal flight trajectory is obtained from an existing nonlinear model. With this …

Influence Of Initial Turbulence Intensity On The Heat And Moisture Transfer Through A Recirculated Air Curtain, Nguyen Quang Van

Doctoral Dissertations

"An air curtain is a directed jet of air separating a controlled space from an environment of different temperature and humidity. This investigation describes the development and verification of an eddy viscosity model which accounts for the influence of the initial turbulence intensity on the transfer of heat and moisture across a recirculated air curtain. The control of the turbulence intensity at the nozzle exit of an air curtain permits control of heat and moisture transfer and therefore the energy required to operate the air curtain.

Both theoretical and experimental studies were made of the recirculated air curtain. An explicit …

1st Umr-Mec Conference On Energy Resources -- Entire Proceedings, University Of Missouri--Rolla

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

No abstract provided.

A Solar-Hydrogen Energy Conversion Scheme For Agricultural Use, R. L. Reisbig, Jack L. Boone, Gordon E. Weiss, Thomas Van Doren

UMR-MEC Conference on Energy / UMR-DNR Conference on Energy

A solar energy activated system is presented which can produce hydrogen and hydrogen-derived fuels (methanol) for use on farms. The device, named "solar-kine", also can produce fertilizer (anhydrous ammonia) as a byproduct of the hydrogen. A cost analysis shows that solar-kine may be mass-producible and sold to farmers for between $7,200 and $14,700. This is equivalent to giving the fanner energy at a price of $1.79 to $3.66 per million BTU's (in 1974 dollars). Presently (Spring, 1974) regular gasoline used in tractors at 43¢ per gallon, represents a cost to the farmer of $3.77 per million BTU's. As oil-based fuels …

The Effect Of Contact Angle, Surface Roughness, And Adsorption Of Heterogeneous Nucleation Of Condensing Water, Prafulla Chandra Mahata

Doctoral Dissertations

"Condensation of water vapor on various surfaces was studied experimentally. It was found that supersaturations as high as 25% were required to initiate condensation on hydrophobic surfaces. The supersaturation data agreed qualitatively with the Volmer theory of heterogeneous nucleation. The influence of adsorption of water vapor was found to be small. Surface roughness caused a little reduction in the critical supersaturation"--Abstract, page iii.

Measurements Of Condensation Coefficient Exhibited By Water Drops Grown On Rural Cloud Nuclei, Abbas M. Sinnarwalla

Doctoral Dissertations

"Values of condensation coefficient, ß, were experimentally determined for water drops grown on cloud nuclei in atmospheric air samples. The measured quantities were supersaturation, final drop size (6 to 7.5 µm radius), and time to grow from near dry radius to final radius. The drops were grown in a vertical-flow thermal diffusion chamber, at supersaturations near 0.5 and 1.0%. The final drop sizes were large enough so that ß did not depend upon the size of the nucleus producing a given drop. The average value of ß was 0.025 with a standard deviation of about 0.01"--Abstract, page 2.

Transient Thermal Stresses In A Sphere By Local Heating, J. B. Cheung, T. S. Chen, K. Thirumalai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of transient thermal stresses in a solid, elastic, homogeneous, and isotropic sphere is solved for uniform and nonuniform, local surface heating. The temperature solutions are obtained by using separation of variables and integral transformation. The corresponding thermal stresses are derived by superposing a particular displacement potential function on Boussinesq solutions. Numerical solutions for two particular cases of localized heating of a typical brittle spherical solid have been obtained and presented. The results indicate a tensile stress concentration in the interior of the solid below the heated zone. © 1974 by ASME.

Two Dimensional Radiant Interchange Between Two Isothermal Semi-Infinite Parallel Strips., Stanley Earl Mckinney

Masters Theses

"Four straight forward solution methods were used to determine the two-dimensional variation of the radiosity on two identical constant temperature, gray, semi-infinite parallel strips. Physical convergence parameters were developed for the one-dimensional case and extended to two dimensions. A study using these parameters was undertaken to identify the preferable method. The solutions obtained with this "best method" agree well with the one-dimensional solutions. The error is estimated to be less than one percent" -- Abstract, p. ii

A Finite Element Method For Three-Dimensional Analysis Of Metal Forming, Nguyen Don Phu

Doctoral Dissertations

"The importance of metal forming by extrusion was reviewed. A Finite Element Approach was developed to analyze extrusion processes. A brick type linear element and the Upper Bound theorem were used to analyze the extrusion of a cylindrical billet into a square cross-section prism. A minimization technique for a non-linear functional with linear constraints was developed. Different types of boundary conditions were also formulated. A frictionless extrusion was simulated using the computer program developed. Velocity profiles at different sections of the deforming solid were obtained and an average extrusion pressure was predicted for a given area reduction ratio.

Extrusions from …

A Study Of Some Heuristic Models For Predicting The Reflection From Spherical Surfaces., Bruce Wayne Rau

Masters Theses

"Four heuristic models' available for predicting the behavior or radiation Non regularly reflected from spherical surfaces have been studied. The four models include: the classical Lambert, the s-factor as deduced by Look, the Lommel-Seeliger, and the Euler's approach. Because each of these analyses was deduced for flat plate geometry, it was first necessary to integrate these flat plate expressions over the surface of a sphere to develop appropriate expressions for the power rejected from the surface of a sphere based upon e ach of the above theories. As an integral part of this investigation, various basic quantities were listed (i. …

Data Acquisition And Analysis System For Computer Modal Analysis Of Automotive Exhaust Emissions., Edward Leroy Mabie Jr.

Masters Theses

"A data acquisition and reduction method for modal analysis of undiluted automotive exhaust emissions is presented. 'The procedure on which this method is based ·wa.s developed and presented in a. paper by Donald L. Stivender, in 1971, entitled, "Development of a Fuel-Based Emission Measurement Procedure." This method is presented as a. viable a.1ternative to the diluted constant volume sample by bag collection technique specified in the federal test procedure for emissions from light duty vehicles.

The instrumentation used for the acquisition of data was the type normally used for automotive emission studies. The four instruments used for exhaust gas analysis …

The Control Of Noise In Urban Areas., Edwin Eugene Frye Jr.

Masters Theses

"Noise has recently been labeled the 'fourth pollutant' and defined by some as the 'unwanted sound' that pervades our work environments and the privacy of our homes. This concern for noise and its effects has resulted from our nation's increasing population density, the increasing use of mechanized conveniences, the influx and growing use of mass transportation systems, and the public's awareness that noise not only 'annoys' and can increase everyday tensions and anxieties, but at certain levels can cause permanent hearing loss.

In order to curb the 'noise problem' legislators and municipal representatives began applying legal controls to noisy activities …

Effect Of Sweeping Sinusoidal Excitation On Nonlinear Dynamic Systems., Md. Mosharraf Hossain

Masters Theses

"The response of viscous damped, cubic spring systems to excitations having exponentially varying frequency cannot be written in a closed form. This report summarizes a numerical investigation of hardening and softening cubic systems influenced by these excitations and provides information concerning the effects of varying viscous damping, system nonlinearity, and excitation sweep rate on system behavior near resonance. Results are reported in terms of maximum response attained during sweeping and the frequency at which maximum response occurs.

It has been found that if hardening cubic systems are subjected to sweeping excitations wherein the frequency sweeps down through resonance, the maximum …

Design Of A Medium Pressure Hydraulic Coal Mining Machine Power Unit System., William Rudolph Heincker

Masters Theses

"In this thesis the design of the major components of a medium pressure hydraulic coal mining machine is presented. The machine is to produce water jets operating at a continuous pressure of 10,000 psi with a total flow rate of 47.8 gpm. This machine is being used to mine coal from an underground longwall coal face, with an expected output of 7 tons per minute.

The primary elements of the hydraulic coal mining machine are the power source, the pump, the cutting head, and the secondary plow supporting structures. The power source will be a British Jefferey-Diamond (BJD) Supermatic electric …

Two-Dimensional Radiative Transfer In Semi-Infinite Isotropically Scattering Medium., Thomas Lee Linsenbardt

Masters Theses

"Two-dimensional radiative transfer in a semi-infinite medium has been investigated. The medium was considered to be homogeneous, absorbing, non-emitting, and isotopically scattering. Cosine, step, and finite strip variations of collimated and diffuse incident radiation were considered. Collimated incident radiation was restricted to lie in planes perpendicular to the direction of its spatial variation.

Expressions for source functions, fluxes, and intensities at the boundary and inside the medium were obtained by assuming cos foe varying incident radiation. This assumption allowed the two-dimensional problem to be reduced to a one-dimensional integral equation for the source function. This integral equation vias transformed into …

Two-Dimensional Radiant Interchange In A Non-Isothermal Cavity Formed By Two Semi-Infinite Parallel Plates., Robert David Allen

Masters Theses

"Two-dimensional radiant interchange between non-isothermal, gray diffuse surfaces with non-uniform radiosity have been investigated for a cavity formed by two semi-infinite parallel plates. The problem is solved for two specific emissive power distribution models. Both emissive power distributions decay exponentially with depth into the cavity. The first emissive power distribution varies in a cosine manner across the front of the plates and the second has a step variation across the front of the plates.

For the cosine varying model, separation of variables and Ambarzumian's method are applied to obtain an integro-differential equation for the radiosity inside the cavity, an integral …

Development Of A Four Channel Cloud Nucleus Spectrometer., Larry Allan Brunner

Masters Theses

"A four-channel vertical flow thermal diffusion chamber for use as a cloud nucleus counter is described. The droplets in each channel are photographically counted. The instrument provides about 20 seconds of available growth time, which enables better distinction of active droplets than does ii the conventional horizontal chamber. Droplet growth calculations show that the uncertainty in droplet count due to limited available growth time is negligible for supersaturations above 0.3% but increases rapidly as the supersaturation is lowered below 0.3%. For example, at 0.1% supersaturation, the uncertainty is -27% to +38% in the drop count. The possible error in supersaturation …

Application Of An Inverse Heat Conduction Technique To A Simulated Injection Mold., Noel Joy Rytter

Masters Theses

"An analytical model was constructed to investigate the heat transfer in an injection mold for which the temperature was controlled by a special mold heating-cooling process. Several techniques were used to test the validity and accuracy of the analytical model of the mold and to explain some singularities that occurred. It was determined that the thickness of the plastic part being molded is the primary factor affecting the minimum cycle time for the molding operation. Also, abrupt changes in temperature on the molding surfaces are very difficult to obtain because this requires drastic temperature changes for the working fluid that …

Thermal Fragmentation Of Rock - The Influence Of Temperature Dependent Material Properties., James Dale Scheller

Masters Theses

"This investigation is concerned with a thermal rock fragmentation system employing heat to create subsurface thermal inclusions. The effectiveness of this system as applied to three different rock types is studied. The rock types are Dresser basalt, Charcoal gray granite, and Sioux quartzite. Also, the influence of temperature dependent material properties is investigated.

The actual three-dimensional problem of in situ rock fragmentation involves parallel rows of equally spaced holes drilled to a constant depth. A heat source at the bottom of each hole creates a thermal inclusion resulting in a stress field causing fracture.

Axisymmetric models of the fragmentation system …

Liquid Metal Heat Transfer In Longitudinal Flow Along A Cylinder And Flat Plate., Marvin Eugene Lohmann

Masters Theses

"In this investigation an analytical study is performed to determine the effect of axial heat conduction on laminar forced convection for longitudinal flow of liquid metals along a horizontal cylinder and a flat plate. ii

The flow and thermal boundary layers for the problems under consideration do not admit similarity solutions, the non-similarity arising from the transverse curvature; ε = (4/R) (vx/u _∞) ^½ of the cylindrical surface and from co the effect of the axial heat conduction expressible as Ω = 1/Pe_x , where Pe_x is the local Peclet number. The governing conservation equations along with …

Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure., Dennis Charles Edwards

Masters Theses

"The analytical and experimental investigations presented here determined natural frequencies and system behavior of a full journal bearing loaded dynamically and with oil supply pressure held constant.

The analysis showed that the bearing could be viewed as two independent second-order systems acting perpendicular to each other. This yielded an underdamped bearing for ε_O < 0.5747 and an overdamped bearing for 0.655 < ε_O < 0.675. The analysis also showed the bearing to be unstable beyond ε_O = 0.675.

The analysis, however, is limited to a full journal bearing with an oil supply pressure of 20 psig. and therefore, various supply pressures should be tested to yield an overall analysis"- Abstract, p. ii

Combined Forced And Free Convection On A Vertical Cylinder And Flat Plate, Aleksandros Mucoglu

Masters Theses

"In the study of fluid flow over heated surfaces, it is customary to neglect the effects of buoyancy force when the flow is horizontal. However, such a practice is not justified when the forced flow is along an inclined or a vertical surface, because under these conditions the buoyancy force modifies considerably the flow field and hence the heat transfer rate from the surface. Such a flow is termed combined forced and free convective flow.

The present study is concerned with the effects of buoyancy force on forced convection along an isothermal vertical cylinder and a flat plate. This type …

Flow Field And Heat Transfer For Developing Flow Of Molten Glass In A Duct, Russell Ralph Beckmeyer

Masters Theses

"The molten glass flow (temperature range 1300 to 1500°C) in the entrance region of a duct was investigated with numerical methods. The mathematical model was restricted by assuming: (1) two dimensional, steady state, (2) Newtonian fluid, variable viscosity, and (3) Rosseland approximation. In addition, appropriate use was made of the fact that the Reynolds number is small and the Eckert number is very small. The inclusion of temperature dependent viscosity and a Rosseland approximation for radiation produced from the mass, momentum, and energy equations a system of coupled, nonlinear, partial differential equations which were solved by an iterative finite difference …

Laser Holographic Interferometric Investigation Of Heat Transfer About An Isothermal Vertical Flat Plate, Richard Michael Quinlisk

Masters Theses

"A study of the laser holographic interferometer was conducted to compare heat transfer data obtained with the device to standard free convection boundary layer theory. The system studied was an isothermal vertical flat plate. The interferometer was used to obtain fringe patterns of the boundary layer at the plate surface.

Data from the holographic interferograms were recorded by making conventional two-dimensional photographs of the holographic images.

The optical data are shown to have a good correlation to Von-Karman theory. Values of the boundary layer thickness, temperature distribution, and heat transfer were compared. An attempt was made to probe the boundary …

Two-Dimensional Radiative Transfer In A Finite Scattering Mediu, James Warren Koewing

Masters Theses

"Exact formulations are presented for the source function, intensity and flux for a two-dimensional, isotropically scattering medium of finite thickness. Spatially varying collimated and diffuse radiation of the following types are incident on the medium: (1) cosine varying, (2) semi-infinite step, (3) step at the origin, and (4) finite strip. The solutions for the cosine varying collimated boundary condition are used to construct solutions for the other boundary conditions. The two-dimensional integral equations are reduced to one-dimensional equations by separating variables. Through a series of transformations, the one-dimensional equations are put into a form in which the source function, intensity …

Diurnal Solar Heating And Cooling Of A Water Reservoir, Stephen Patrick Lepper

Masters Theses

"The transient diurnal heating of a water reservoir by solar radiation; and its cooling by surface convection, evaporation, and radiation emission was analytically modeled. The directional and spectral properties of the incident solar radiation, the air-water interface, and the selective attenuation of radiant energy by the water were properly included in the analysis. The diurnal vertical temperature distribution was predicted by numerically solving the energy equation using a finite difference technique. It was determined that the surface boundary conditions and the selective absorption of radiant energy by the water strongly influence the thermal stratification of stagnant water.

The diurnal compensating …

Vibration Characteristics Of Free Thin Cylindrical Shells, Floyd M. Cunningham, D. E. Leanhardt

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper considers the flexural vibrations of free thin circular cylinders. A frequency equation is derived using free-free characteristic beam functions to represent the variation of mid-surface shell displacement components, u, v and w, with respect to the axial direction. Timoshenko strain-displacement relations for thin cylinders are used to determine elastic vibratory strain energy. Energy methods are applied to obtain the frequency equation and associated amplitude ratios for each of its roots. This energy solution is checked experimentally using a vibration exciter and numerically using the SABOR IV finite element program. With minor modification, the frequency equation conforms to the …

Numerical Modeling Of The Early Stage Of Cloud Formation In A Simulation Chamber, Adel Nassif Saad

Doctoral Dissertations

"A numerical model has been developed to simulate the growth of cloud droplets by condensation upon a spectrum of hygroscopic nuclei. The model is applicable to cloud simulation chamber conditions as well as to the study of the role of these nuclei on cloud base microstructure.

Equations are given for the growth by condensation of water vapor on a population of hygroscopic nuclei in a volume being cooled by expansion. The equations are integrated simultaneously, using Hamming's modified predictor-corrector method for given initial conditions, to obtain the droplet size distribution, temperature, pressure, supersaturation, and liquid water content. Temperature fluctuations, sedimentation …

An Analytical And Experimental Study Of The Dynamic Response Of A Press, Woosoon Bai

Doctoral Dissertations

"This dissertation presents a simplified mathematical model and computer simulation of the vertical motion of a press. The model is verified by comparing simulation results with actual field measurements.

Using this model, the computer simulation is then extended to study the dynamic response of a bolted press, one with loosened anchor bolts, and one which is isolated. Press performance, in terms of acceleration of the press, velocity of its foundation, and forces transmitted to the foundation, is analyzed in relation to the foundation mass and the stiffness of the isolators, where applicable. Comparative performances of the presses secured by the …

Direct And Inverse Heat Conduction In Rock Materials Using The Finite Element Method, Vernon Dale Allen

Doctoral Dissertations

"A finite element method is presented for solution of direct and inverse heat conduction problems in rock materials. Finite element programs for direct and inverse heat conduction problems were developed and demonstrated. Flow charts are given for the finite element programs.

The direct finite element heat conduction program changes material properties with temperature to approximate the temperature dependent properties of rock materials. An example problem was solved by the finite element method and also using Kirchoff's transformation. The finite element solution compared quite well with the Kirchoff transformation solution.

The inverse method utilizes the direct finite element heat conduction program …