Aerospace Engineering Commons^™

Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar

Mechanical and Aerospace Engineering Faculty Research & Creative Works

To Measure Size Distributions of Sub micrometer Aerosols with an Electrical Differential Mobility Analyzer (DMA) Requires an Inversion Procedure. the Knutson (1976) and the Hoppel (1978) Inversion Procedures Were Numerically Investigated for the Case of Log-Normal Aerosol Size Distributions. It Was Found that the Hoppel Procedure Converges to the Same Result as that Given by the Knutson Procedure. the Computational Range for Geometric Mean Diameter (Χ_g) Was 0.025-0.25 Μm, and for Geometric Standard Deviation (Σ_g) Was 1.1-2.4. the Inversion Error Was Found to Be Greater Than 10% in Certain "Forbidden Zones" of Χ_g and Σ …

Estimation Of Water And Energy Requirements For Ground Water Heat Pumps In The United States, Ronald H. Howell, Harry J. Sauer Jr.

UMR-DNR Conference on Energy

No abstract provided.

Feasibility Study For A Municipal Refuse To Energy Plant, Archie W. Culp Jr.

UMR-DNR Conference on Energy

No abstract provided.

Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Concentrations of Cloud Condensation Nuclei in the Atmosphere Were Measured at Rolla, Missouri, Near Ground Level. a Total of 432 Spectra Were Measured over a 10-Month Period. No Consistent Seasonal or Diurnal Pattern Was Observed. Possible Implications for Fogs and Stratus Clouds and for Nuclei Chemical Composition Are Discussed.-From Authorscloud Condensation Nuclei Rolla Missouri Fogs

Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The combined effects of buoyancy forces from thermal and species diffusion on the heat and mass transfer characteristics are analyzed for laminar boundary layer flow over a horizontal flat plate. The analysis is restricted to processes with low concentration levels such that the interfacial velocities due to mass diffusion and the diffusion-thermo/thermo-diffusion effects can be neglected. Numerical results for friction factor, Nusselt number, and Sherwood number are presented for gases having a Prandtl number of 0.7, with Schmidt numbers ranging from 0.6 to 2.0. In general, it is found that, for the thermally assisting flow, the surface heat and mass …

Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The problem of the indentation of a rubberlike layer bonded to a rigid cylinder and indented by another rigid cylinder is analyzed. The rubberlike layer is assumed to be made of a homogeneous Mooncy-Rivlin material. The materially and geometrically nonlinear problem is solved by using the finite-element code developed by the author. Results computed and presented graphically include the pressure profile at the contact surface, stress distribution at the bond surface and the deformed shape of the indented surface. © 1980 by ASME.

Aerodynamic Study Of Dual Lifting Surfaces, Kamran Rokhsaz

Masters Theses

"Aerodynamic characteristics of two-dimensional dual airfoil systems have been investigated in an incompressible flow field in the area where improved aerodynamic characteristics are realized, due to the flow field coupling of the two airfoils. A simple analytic model has been developed to demonstrate some of the basic coupling effects in such systems. Laplace's differential equation for the stream-function has been solved numerically to determine the potential flow about dual airfoil geometries of different gap, stagger, and decalage. Two numerical methods have been employed; a finite-difference approach in Cartesian coordinates, for which the mixed boundary conditions have been transformed to the …

Demonstration Of Low Btu Gasification Using The Grow Facility, V. J. Flanigan, Y. Omurtag

UMR-DNR Conference on Energy

No abstract provided.

Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Nucleation Experiments with Monodisperse NaCl Aerosols Showed Good Agreement with the Kohler Theory Relating the Critical Super-Saturation S//c to the Dry Size. Aerosols Produced by Condensing NaCl Showed the Same S//c as Those Produced by Evaporating Aqueous NaCl Solution Droplets. This Indicates that If There is an Energy Barrier in Going from a Dry NaCl Particle to a Solution Droplet, This Energy Barrier is Small. the Fact that the Evaporation Aerosol Particles Are Cubical Crystals and the Condensation Aerosols Are Amorphous Spheres is Shown to Make No Difference in the Nucleation Threshold. the Investigation Also Gives Insights into the Performance …

Testing Of Solar Collectors By A Standard Method, Harry J. Sauer Jr., Bassem F. Armaly

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

A description of the recently adopted standard for testing solar collectors "ASHRAE STANDARD 93-77, METHOD OF TESTING SOLAR COLLECTORS BASED ON THERMAL PERFORMANCE" is presented. Results from the standard could be used to simulate the transient performance of an installed solar system.

Performance Of A Dual-Range Cloud Nucleus Counter., Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An Instrument for Measuring the Concentrations of Cloud Condensation Nuclei as a Function of Nucleus Critical Supersaturation (S//c) is Described. in the Range 0. 1% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Instrument is Operated as a Vertical Flow Thermal Diffusion Chamber. in the Range of 0. 016% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Chamber is Operated at 100% Humidity, and the Equilibrium Radii of the Nuclei Are Measured with an Optical Counter. This Paper Presents a Large Body of Data Taken in the Laboratory to Evaluate the Performance …

A Small Horizontal Axis Wind Turbine Feeding Power Into The Utility Grid, G. C. Thomann, M. Jong, M. H. Snyder

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

A small horizontal axis wind turbine, with about a 2 kW power output, was constructed to convert wind energy into AC power to be fed into the utility grid. The machine is intended to model operation of the larger wind generators now being built. The variable pitch rotor is 18 ft in diameter and has a GA(W)-1 blade airfoil. The rotor is fabricated from sitka spruce mounted on a commercial propeller/hub system. Rotor speeds of from 75 to 150 rpm are used in operation. A chain drive and helical gear drive system steps up rotor speed to 1800 - 3600 …

Airfoil Data For Use Of Wind Turbine Designers, Melvin H. Snyder

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

This paper reviews design procedures for wind-axis turbine rotors. An "on-design" routine for rotor blade design is presented as well as an "off-design" performance calculation program. Resulting from this review are analyses of desirable characteristics of airfoil sections and of types of data which rotor designers need. Included in the paper are airfoil characteristics for candidate blade sections including 360 degree data for GA(W)-1 and GA(W)-2 airfoils.

Low Head Power Generation With Bulb Turbines, J. L. Carson, R. S. Samuelson

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

Because of uncertainties, delays, and high costs associated with alternative electric energy sources, many agencies responsible for generation of electrical power are investigating means of replacing or supplementing their existing hydroelectric facilities. In the head range between 10 and 60 feet, the bulb-type generating unit, in which the generator is enclosed in a metal capsule within the water passage, has many advantages, including higher efficiency and lower cost, over other types of turbines. Two of the municipalities in the United States which have recently conducted feasibility studies for installing bulb turbines in their systems are the City of Idaho Falls, …

Mixed Convection Across A Horizontal Cylinder With Uniform Surface Heat Flux, A. Mucoglu, T. S. Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Optimal Cantilever Dynamic Vibration Absorbers, R. G. Jacquot, J. Earl Foster

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work considers the use of a double-ended cantilever beam as a distributed parameter dynamic vibration absorber applied to a single-degree-of-freedom system in the presence of sinusoidal forces. The problem is analyzed exactly and by an energy approach using a single mode approximation for the cantilever beam. The results for both techniques compare favorably and damping is introduced in the form of a complex beam modulus. Optimal tuning and optimal damping parameters are found for a given ratio of absorber mass to main mass. © 1977 by ASME.

Studies Of Vibrational Surface Modes In Ionic Crystals. I. Detailed Shell-Model Studies For The Unrelaxed (001) Face Of Seven Crystals Having The Rocksalt Structure, T. S. Chen, F. W. De Wette, G. P. Alldredge

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present a comprehensive, unified account of the lattice dynamics of unrelaxed (001) faces of seven crystals having the rock salt structure, three of which have an absolute gap between the acoustical and optical bulk bands (RbF, RbCl, and NaI) and four of which have overlap between these bulk bands (NaF, NaCl, LiF, and MgO). The results are obtained from calculations of the normal modes of a thin crystal film in which the ionic interactions are described by the rigid-shell model. An outline of the formulation of the shell model for the film is given, and the rapid convergence of …

A Closed-Form Solution For The Radiosity At The Edge Of A Rectangular Cavity, Alfred L. Crosbie

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure, D. C. Edwards, N. Khorzad, Charles L. Edwards

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The analytical and experimental investigations reported here deal with the natural frequencies and system behavior of a full journal bearing subjected to a small sinusoidal load superimposed on a large unidirectional static load. The analysis, verified by experimentation, shows that the bearing can be regarded as two independent second-order systems acting perpendicular to each other. The variable coefficients of the equations of motion cause the bearing to behave as an underdamped system for low values of static eccentricity ratio to, and as an overdamped system for intermediate values of to. The bearing tends to be unstable above a particular to. …

Development Of Helicopter Flight Path Models, Alfred Fermelia, Donald A. Gyorog, V. J. Flanigan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The objective of this paper is to present general techniques for simulating helicopter flight trajectory response. During flight the pilot manipulates the controls either to trim the helicopter for steady flight by balancing the external forces and moments or to produce a desired maneuver by controlling the unbalance of these forces and moments. Discussions of the physical phenomena involved with the aerodynamics of the rotors and fuselage are given in [1] through [3]. The simulated control function will be composed forward-aft cyclic, lateral cyclic, pedal, and collective. This control will be represented by the vector

Deformation Produced By A Simple Tensile Load In An Isotropic Elastic Body, R. C. Batra

Mechanical and Aerospace Engineering Faculty Research & Creative Works

It is shown that a simple tensile load produces a simple extension provided the empirical inequalities (Truesdell and Noll [1], eqn. 51.27) hold. © 1976 Noordhoff International Publishing.

Bit Penetration Into Rock-A Finite Element Study, J. K. Wang, T. F. Lehnhoff

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The sequence of rock failure mechanisms and quantitative information on stress, displacement and material failure in the process of bit penetration have been obtained through computer simulation. A finite element approach has been developed to simulate bit penetration from bit-rock interaction to chip formation. A mathematical rock failure model, based on available rock failure experiments, has been proposed to represent post-failure rock behavior and applied in the penetration simulations. The finite element code was developed for two-dimensional plane strain problems to consider non-linear material properties, geometric non-linearity, and fracture propagation. An anistropic element as well as variable stiffness and stress …

Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Performance of the Conventional Horizontal Plate Thermal Diffusion Chamber as a Cloud Nucleus Counter Was Studied. Numerical Calculations Were Performed in Order to Follow the Simultaneous Drop Growth and Sedimentation in the Spatially and Temporally Nonuniform Supersaturation Field. the Effect of Nuclei Distribution and Smallest Detectable Drop Size Were Investigated. the Results Indicate Order of Magnitude Uncertainty in the Count at 0. 1% Supersaturation, and a Factor of 2 Uncertainty at 1. 0% Supersaturation.

Mie Scattering Computations For Moderately Large Spherical Particles, Dwight C. Look

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

The Effects Of Main-Flow Radial Velocity On The Stability Of Developing Laminar Pipe Flow, F. C.T. Shen, T. S. Chen, L. M. Huang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In studying the stability due to axisymmetric disturbances of the developing flow of an incompressible fluid in the entrance region of a circular tube, a generalized version of the Orr-Sommerfeld equation was derived which takes account of the radial velocity component in the main flow. The new terms in the generalized Orr-Sommerfeld equation are inversely proportional to the Reynolds number. The resulting eigenvalue problem consisting of the disturbance equation and the boundary conditions was solved by a direct numerical integration scheme along with an iteration procedure. Neutral stability curves and critical Reynolds numbers at various axial locations are presented. A …

The Application Of Impact Dampers To Continuous Systems, Ranjit K. Roy, Richard D. Rocke, J. Earl Foster

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Experimental models were tested in the laboratory and computer programs were developed to calculate response by two separate approaches. Results from calculations agreed favorably with experimental tests. Curves presented show the response to be expected for values of significant system parameters and enable the user to apply impact dampers to these types of continuous systems. © 1975 by ASME.

Thermal Stresses In A Sphere Due To Local Heating Followed By Complete Cooling, T. S. Chen, K. Thirumalai, J. B. Cheung

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

Photoionization Of The 6p32,122 Fine-Structure Levels In Cesium, Kaare J. Nygaard, Robert E. Hebner, James A. Jones, Robert J. Corbin

Physics Faculty Research & Creative Works

The relative photoionization cross sections for cesium atoms selectively excited to the 6P32,122 states have been measured in a triple-crossed-beam experiment. A cesium discharge lamp produced resonant wavelengths of 8521 and 8944 for the excitation process. A Hg-Xe lamp combined with a grating monochromator was used for the actual ionization in the wavelength region from 2500 to 5000. Background counts due to photoionization of ground-state cesium atoms and dimers as well as various surface effects were discriminated against by chopping the excitation light source. The data are compared with results from radiative-recombination measurements in which the fine-structure levels are not …

Experimental Investigation Of Supporting Wire Interference Effects In The Supersonic Near Wakes Of Slender Bodies., Dale M. Pitt

Masters Theses

"It is generally recognized that the presence of a model support sting i s likely to affect the model's base pressure and wake characteristics. The use of a wire-supported model is usually relied upon to obtain minimum disturbance measurements in the model's wake. Investigations into the disturbances caused by different size supporting wires have been conducted with the use of a 16-degree wedge and 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. Pitot pressure traverses were made in the …

A Study Of The Potential Performance Improvements Available From The Ga(W)-1 Airfoil As Compared To The Naca 2412 Airfoil., Robert Keith Rice

Masters Theses

"A direct comparison of the current NACA 2412 section general aviation airfoil and the recently developed GA(W)-1 airfoil was conducted in the University of Missouri - Rolla's subsonic wind tunnel. Finite aspect ratio performance of both airfoils equipped with 30 percent chord flaps was studied to predict possible performance gains for general aviation aircraft available from the GA(W)-1 section.

Results show that the NACA 2412 airfoil with a standard slotted type flap gives a maximum lift coefficient of 1.88 with the flap deflected 30 degrees and a test Reynolds number of 4.Sxl0 5 based on wing chord. The GA(W)-1 section …