Aerospace Engineering Commons^™

A Parametric Investigation Of The Validity Of 1/25 Scale Automobile Aerodynamic Testing., Marvin Eugene Doberenz

Masters Theses

"Wind tunnel tests have been performed measuring the aerodynamic forces and underbody boundary layer profiles for 1/25 scale models. The trends of the force coefficients with Reynolds number, the underbody boundary layer profiles, and the influence of the ground plane boundary layer on the force coefficients of small-scale models has been shown to be similar with previous results from larger models. This study has shown the usefulness of small-scale models for parametric studies of automobile aerodynamics. The agreement of the data with previous results, also supports the possih1lity o f a method of correction for boundary layer growth on fixed …

Insoluble Condensation Nuclei: The Effect Of Contact Angle, Surface Roughness And Adsorption., P. C. Mahata, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Condensation of Water Vapor on Various Surfaces Was Studied Experimentally. for Surfaces with an Air-Water Contact Angle Theta Less Than 20 Degree, the Experimentally Determined Values of Critical Supersaturation S//c Agreed with Those Given by the Volmer Theory. at Higher Theta, the Experimental Values of S//c Were Below the Volmer Theory Values. When the Applied Supersaturation Was Less Than S//c, Condensation Was Avoided for Periods as Long as 20 H. It Was Determined Both by Experiment and Theoretical Analysis that the Effect of Surface Roughness is to Decrease S//c Only Slightly. These Results Suggest that Most Insoluble Airborne Particles Are …

Measurement Of Growth Rate To Determine Condensation Coefficients For Water Drops Grown On Natural Cloud Nuclei., A. M. Sinnarwalla, Darryl J. Alofs, J. C. Carstens

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Growth Rate Measurements Were Made for Water Drops Grown on Nuclei in Atmospheric Air Samples Taken in Rolla, Missouri. Rolla, Having a Population of 15,000 and Very Little Industry, is Relatively Free of Urban Pollutants. the Measurements Were Made in a Vertical Flow Thermal Diffusion Chamber at Supersaturations of 0. 5 and 1%. the Time to Grow from Near Dry Radius to the Final Radius (6 to 7. 5 Mu M) Was Measured. If One Assumes the Thermal Accomodation Coefficient is Unity, the Measurements Indicate an Average Value of 0. 026 for the Condensation Coefficient. the Temperature Ranged from 22. …

Transport Phenomena In Thermally Stratified Boundary Layers, D. W. Pepper, S. C. Lee

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Studies of heat, mass, and momentum transfer are made to analyze the formation of marine fogs in thermally stratified boundary layers in the atmosphere. The governing partial differential equations of continuity, momentum, temperature, and concentration are used to describe the transport phenomena. An additional equation of turbulence energy is introduced to account for the development of the turbulent motions. Simultaneous solution of this system of equations allows the turbulent exchange coefficients to be treated in the same way as all other dependent parameters. Verification of the theoretical approach is made by comparing the numerical predictions with wind tunnel simulations of …

Experimental Determination Of Improved Aerodynamic Characteristics Utilizing Biplane Wing Configurations, Elmer Carl Olson

Masters Theses

"Improving the aerodynamic characteristics of an airplane with respect to a higher lift coefficient, a lower drag coefficient and a higher lift over drag ratio as a function of angle of attack will make it more efficient, thus conserving energy or improving performance. Investigations were carried out to determine if the aerodynamic characteristics of biplane wing systems could be made more efficient, for low subsonic speeds, than a monoplane of comparable area and aspect ratio. A variable position three-dimensional biplane wing system, and a fuselage that could be fitted with a monoplane wing or the variable position biplane wing system …

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.

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 …

Breakdown Of The Laminar Flow Regime In Permeable-Walled Ducts, E. M. Sparrow, G. S. Beavers, T. S. Chen, J. R. Lloyd

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The stability of laminar flow in a parallel-plate channel having one permeable bounding wall is investigated by means of linear theory. The analysis lakes account of the coupling of the disturbance, fields in the channel and in the permeable material and of velocity slip at the surface of the permeable wall. Complementary experiments are performed in which the breakdown of the laminar regime in flat rectangular ducts is identified from pressure-drop measurements and from flow visualization studies. The experiments cover the range of slip velocities from 15-30 percent of the mean velocity and, in addition, the case of zero slip …

Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A decision-directed (DD) technique for the detection of overlapping PCM/NRZ signals in the presence of white Gaussian noise is investigated. The performance of the DD detector is represented by probability of error PE versus input signal-to-noise ratio (SNR). To examine how much improvement in performance can be achieved with this technique, PE's with and without DD feedback are evaluated in parallel. Further, analytical results are compared with those found by Monte Carlo simulations. The results are shown in good agreement. © 1973, IEEE. All rights reserved.

Parametric Resonance Of A Beam Subjected To A Sawtooth, Axial Force, Alfred George Richardson

Masters Theses

"This study considers the response of a perfectly elastic straight beam subjected to a periodic, non-harmonic, axial load. A two-mode solution is sought and the effects of axial inertia are included in the analysis. General equations of motion for the beam are developed and their stability is studied with the aid of an analog computer. Results are presented in graphical form. Regions of instability are defined for both modes. A region of combination resonance is also found to occur for the case of a two-mode solution with axial inertia. Typical response curves are presented and the effects of axial inertia …

An Optical Detector Of Water Droplets Within A Thermal Diffusion Chamber, Duane Burton Bush

Masters Theses

"A technique is investigated for counting water droplets formed in a vertical plate steady flow thermal diffusion chamber designed to count cloud condensation nuclei. The counting technique utilizes light scattering. The light source is a He-Ne laser. The detector is a photomultiplier tube. The technique differs from that used in instruments manufactured by Bausch and Lomb, Royco, Climet, etc., in that the aerosol is not passed through a capillary tube. Instead, the viewed volume is optically defined.

It was found that in the configuration tested, the viewed volume is not well enough defined for use with polydisperse aerosols, although the …

Engineering And Scientific Manpower- A Scarce Resource For The 1970'S, Merl Baker

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Nonequilibrium Structure Of Argon Shock Waves, Harlan F. Nelson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This theoretical study investigates the influence of (1) the nonequilibrium excited state population in the relaxation region and (2) line radiation in the precursor on shock wave structure by considering strong shock waves propagating at Mach 18 and 24 into a theoretical argon-like gas at a pressure of 1 cm Hg and a temperature of 300°K. The argon atom is modeled as having two bound states plus a continuum, and the calculations include finite atom-atom and electron-atom collisional ionization and excitation rates as well as continuum and line radiation. The electron gas is allowed to be at a different temperature …

Design And Preliminary Testing Of A Rotary Internal Combustion Engine, Frank Darrell Statkus

Masters Theses

"With the advent of legislation against pollution, and rising wage, manufacturing, and materials costs, the prime mover industry is presently intent on developing new economical, non-polluting methods of power. It was the hope of the author that the engine described herein would provide an advancement towards meeting the new requirements. The design and resulting prototype is an eight cylinder rotary internal combustion engine, weighing approximately sixty pounds, and operating on the tour stroke principle. Theoretical calculations were made to determine ideal horsepower, mean effective pressure, and efficiency. Ideal horsepower ranged from 38.7 to 62.8. A dynamic analysis of the pistons …

An Experimental And Numerical Study Of Elastic Strain Waves On The Center Line Of A 6061-T6 Aluminum Bar, J. L. Habberstad, K. G. Hoge, J. Earl Foster

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The elastic strain waves resulting from the impact of two 3/4-in-dia 6061-T6 aluminum bars are studied experimentally and analytically. Experimental data are obtained from strain gages on the center line and outer surface of the bar, located at various distances from the impact end of the bar. Experimental data are compared to numerical results obtained from integrating the exact equations of two-dimensional motion. In general, agreement between the numerical and experimental results is very good. © 1972 by ASME.

An Application Of Bubble Shape Theory To The Determination Of Air Transfer Through Adsorbed Surface Films, Robert A. Medrow

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Reply To The Comments Of H. M. Princen [2], Robert A. Medrow, B. T. Chao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Magnetohydrodynamic Stability Of The Developing Laminar Flow In A Parallel-Plate Channel, T. S. Chen, T. E. Eaton

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Linear stability of the developing laminar flow of an electrically conducting, incompressible fluid in a parallel-plate channel under a transverse magnetic field is investigated. The case of small magnetic Reynolds numbers is treated. The developing flows whose stability characteristics are studied correspond to those induced by a uniform and a parabolic velocity distribution at the channel inlet. The stability of the fully developed Hartmann flow is also reexamined. Neutral stability curves and axial variations of the critical Reynolds number are presented for a range of Hartmann numbers between 0 and 4. It is found that for Hartmann numbers larger than …

Forming Of 7075-T6 Aluminum In High Pressure Environments, Richard L. Pendleton, Robert L. Davis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Plates of 7075-T6 Aluminum have been folded along a major axis in pressure environments of atmospheric, 20,000 psi, and 40,000 psi. A finite element computer program is used to determine the stress state in the plates at various loads. Tension and compression tests conducted in pressure environments up to 70,000 psi were used to construct models using effective stress, effective strain, and pressure as parameters to predict the behavior of the material under various stress conditions. A prediction of the occurrence of fracture in the folded plate was possible using the computer results and the pressure dependent model. As better …

Experimental Studies Of Supporting Wire Disturbances In The Near Viscous Wakes Of Slender Supersonic Bodies, Kenneth Anthony Mirly

Masters Theses

"Wires have often been used as a means of mechanically supporting a model so that its wake will be relatively free of support interference. Such support systems have many advantages over stings and are less costly than magnetic suspension systems. Investigations into the disturbances caused by these supporting wires have been carried out with the use of a two-dimensional flat plate and a wire supported slender cone. The tests were conducted in the University of Missouri-Rolla axisymmetric, supersonic wind tunnel at Mach 3.15, and at a Reynolds number of 2.14 X 10⁶ per inch. Schlieren photography, pitot and static pressure …

A Strain Energy Comparison Of Discrete Modeling For Vibrating Continuous Systems, S. K. Tolani, Richard Dale Rocke

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lumped parameter models commonly used to describe continuous one-dimensional and Bernoulli-Elder beam vibration problems have been compared on the basis of maximum system, strain energy. The consistent mass matrix approach has been included in the comparison. Standard matrix techniques have been employed to mathematically obtain desired solutions. Closed form solutions and solutions via the models to Ike system strain energy were obtained for all systems in three dynamic states: Free vibrations, constant base acceleration, and half sine base acceleration. Behavior of the strain energy errors, in general, were found to be similar to those of the frequency root errors. © …

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 …

An Analog Computer Simulation Of The Flapping Of A Helicopter Hinged Main Rotor Blade, Edward Charles Robinson

Masters Theses

"An analog computer simulation was performed on the Systron Donner SD 40/80 electronic differential analyzer consisting of one panel (SD 40) less three modules augmented by three digital logic modules for iterative operation. The flapping equation was solved in continuous iteration for various values of blade mass and the resultant blade flapping magnitudes and harmonic coefficients were compared in computer plots of the blade tip path plane. A flap compensator was added and the result plotted. Various aerodynamic parameters of the flapping equation solution were plotted"--Abstract, page ii.

A Closed Form Method For Predicting The History Of Circular Orbit Altitude Decay Of A Near-Earth Satellite Including The Effect Of A Dynamic Atmosphere, John Copley Buchholtz

Masters Theses

"A closed form expression for the time to decay between two circular orbit altitudes is developed. The long-term dynamic variation of high altitude atmospheric density is included. The density is approximated as a ratio of two quadratics with the numerator being a function of the time-related exospheric temperature and the denominator being a function of altitude. The 11-year cyclic variation of exospheric temperature is then represented as a piecewise linear function of time. The analytic expression for circular orbit altitude decay rate is developed by describing the energy loss due to atmospheric drag. A point mass representation of the Earth's …

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 …

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 …

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 …

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.

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.