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Lean Burning Spark-Ignition Engines -- An Overview, J. A. Alic

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

Means of improving the thermal efficiency of spark-ignition internal combustion engines through fuel-lean combustion at part-load are discussed. For purposes of comparison and evaluation, lean-burning engines are classified as modified conventional engines, stratified charge engines, and engines using alternative fuels. Particular attention is given to automobile applications because of their importance for conservation of fuels.

The Missouri Miner, September 04, 1975

The Missouri Miner Newspaper

No abstract provided.

Non-Isothermal Mercury Pipe Flow Turbulent Characteristics, T. W. Flaherty, L. L. Eyler, A. Sesonske

Symposia on Turbulence in Liquids

The turbulence structure of fully-developed mercury pipe flow, with and without heat transfer, was studied using hot-film anemometry at Reynolds number of approximately 50,000. Single sensors and slanted multiple sensors were used to obtain the radial distribution of axial fluctuating velocity and temperature quantities. Isothermal data were generally in good agreement with comparable air data indicating similar velocity structure. Temperature intensity data agreed with other data in liquid metals.

Axial and radial turbulent heat flux results were somewhat inconclusive. Spectra and turbulence scales were developed providing a picture of the structure.

Measurement Of The Low-Wavenumber Component Of Turbulent Boundary Layer Pressure Spectral Density, P. W. Jameson

Symposia on Turbulence in Liquids

This paper describes an experiment in which the turbulent boundary layer (TBL) over a flat plate excites bending waves in that plate predominantly through low-wavenumber components in the pressure field having the same wavenumber as the bending waves of the plate. The plate design is such that contributions to the bending waves from the convective peak of the TBL pressure and from acoustic noise are minimal. The level of response of individual modes of the plate is used to measure the intensity of these low-wavenumber spectral components in the TBL wall pressure.

Session Chairman Introductory Remarks, T. J. Hanratty

Symposia on Turbulence in Liquids

No abstract provided.

The Separation Angle For Spheres In A Pipeline, B. Latto, A. Lai

Symposia on Turbulence in Liquids

The results of a series of experiments on the measurement of the angle of separation for flow over steel spheres suspended in a vertical 5.18 cm ID pipeline with and without a drag reducing aqueous polymer solution are presented. Data were obtained for sphere- to-pipe diameter ratios of 0.74 and 0.925 with polymer concentrations of 0, 25, 50, and 100 wppm over a Reynolds number range of 1633 to 29400 for single spheres and trains of up to three spheres rigidly connected. It was found that relatively dilute polymer solutions can considerably affect the separation angle. Furthermore, that the angle …

The Physical Background For Hot-Film Anemometry, G. Comte-Bellot

Symposia on Turbulence in Liquids

Thin film probes have been used for more than a decade to investigate turbulence, mostly in liquids. Many improvements have been achieved in the technique. Some problems still remain, however, so that the use of hot-film anemometers is not as straightforward as would be expected at a time when numerous ready-to-use probes and associated electronic equipment are commercially available. The following points should be discussed: aerodynamic perturbation caused by the probes, direct experimental check of the frequency response of constant temperature anemometers in the case of small fluctuations, dynamic non-linear behavior of constant temperature anemometers and heat transfer from hot …

Elucidation Of Burst Phenomena In Turbulent Boundary Layers Through Coherent Structure, W. W. Willmarth

Symposia on Turbulence in Liquids

The present knowledge of the turbulent structure of boundary layers is reviewed and summarized. The work of several primary investigators of the bursting phenomenon is discussed. Models for the coherent structure are proposed based on the results of these investigations.

Compliant Wall Surface Motion And Its Effect On The Structure Of A Turbulent Boundary Layer, R. L. Ash, D. M. Bushnell, L. M. Weinstein, R. Balasubramanian

Symposia on Turbulence in Liquids

The status of the continuing compliant wall drag reduction research at NASA-Langley Research Center is discussed. Preliminary surface motion calculations are reported along with compliant surface design concepts and their numerical models. A compliant drag reduction theory based on stabilizing the turbulent substructure is proposed and previous experiments have been examined relative to that theory. Results of recent low speed compliant surface experiments have been reported which include initial attempts to measure local compliant surface motion.

Front Matter, University Of Missouri--Rolla

Symposia on Turbulence in Liquids

No abstract provided.

Energy Spectrum And Turbulent Scales In A Plane Air Jet, V. W. Goldschmidt, M. F. Young

Symposia on Turbulence in Liquids

The energy spectra and longitudinal length scales measured in a free plane jet are presented. The actual convective velocity was used in determining the scales. The results show a universal spectral distribution along the axis but no obvious similarity in the large scale motion off the axis. The results are limited to x/D < 60. The measured scales suggest a noticeable increase of the microscale along the lateral coordinate but an essentially constant value along the axis. However the macroscales, increasing linearly along the axis do not show any similarity off the axis.

Two-Point, Two Component, Velocity Measurements In Turbulent Pipe Flow, J. S. Cintra Jr., B. G. Jones

Symposia on Turbulence in Liquids

An experimental study of the turbulent velocity field structure was performed in a pipe flow. The primary objective of this study was to provide a detailed velocity field structure, under isothermal conditions, for use as a reference condition for later investigations of the interactions between fluctuating velocity and temperature fields, under non-isothermal conditions, in turbulent pipe flow.

Two-point, two-component (u₁ and u₂) velocity correlation measurements were made with hot-film ('x' probes) anemometers separated in the radial direction as well as two-point axial component correlation measurements with axial separation.

The fluctuating signals were analyzed digitally and both space …

Hot-Film Anemometry In Air-Water Flow, J. M. Delhaye, J. P. Galaup

Symposia on Turbulence in Liquids

The paper presents local measurements of void fraction and liquid velocity in a steady-state air- water bubbly flow at atmospheric pressure. Use is made of a constant temperature anemometer and of a conical hot-film probe.

The signal is processed with a multi-channel analyzer. Void fraction and liquid velocities are determined from the amplitude histogram of the signal.

The integrated void fraction over a diameter is compared with the average void fraction along the same diameter obtained with a γ-ray absorption method.

The liquid volumetric flow-rate is calculated from the void fraction and liquid velocity profiles and compared with the indication …

Measurement Of Both Gas And Particle Velocity In Turbulent Two-Phase Flow, D. E. Stock, J. T. Jurewicz, C. T. Crowe, J. E. Eschbach

Symposia on Turbulence in Liquids

A laser-Doppler anemometer was used to measure the velocity of both the gas and particles in a turbulent two-phase flow for conditions when the distribution of the velocities of the two phases overlaps. The velocities from the two phases are separated by comparing the Doppler amplitude to the pedestal amplitude. Results of the measure of the gas-particle flow downstream of a nozzle mounted in a circular pipe are presented.

Liquid Turbulence And Its Measurement, R. L. Humphrey

Symposia on Turbulence in Liquids

This paper covers several principles which have been successfully developed over the past few years and used in the measurement of liquid flows. In particular, ultrasonics, electro-magnetics, thermal heat transfer and optical light transmission will be discussed. Each concept will be covered by basic definitions and laws, theory of operation and application where measurement parameters will be highlighted, thus allowing the user to choose the best instrument to fit his experimental needs.

Characteristics Of Laser Anemometer Signals And Frequency Demodulators For Highly Seeded Flows, R. V. Edwards

Symposia on Turbulence in Liquids

An analysis of the general characteristics of laser anemometer signals for liquid flows is made. Three detection schemes are analyzed:
(1) Spectral analysis of the photodetector output,
(2) frequency trackers, and
(3) counters
Where known, the strengths and weakness of each method are analyzed.

Turbulence Effects Upon Laser Propagation In The Marine Boundary Layer, K. L. Davidson, T. M. Houlihan

Symposia on Turbulence in Liquids

Shipboard measurements of small scale temperature and velocity fluctuations have been accomplished to determine optical wave propagation properties of the marine boundary layer. Measurements were recorded for ocean conditions in Monterey Bay and in the confines of the Pacific Missile Range. Laser beam propagation measurements were performed in conjunction with the meteorological measurements.

Periodic And Random Excitation Of Streamlined Structures By Trailing Edge Flows, W. K. Blake

Symposia on Turbulence in Liquids

This paper is an examination of semi-empirical techniques which are shown to be effective in predicting the response of hydrofoils to flow excitation. Examples are given for buffeting by inflow turbulence, excitation by the boundary-layer pressures on the hydrofoil, and linear and non-linear excitation by vortex street formation in the wake. Co-ordinated aerodynamic and hydrodynamic measurements are used in Reynolds number - scaled experiments to determine both the flow induced forces and the hydro-elastic behavior on cantilever struts. An analytical formulation based on normal mode theory is used to combine the results.

Local Mass Transfer In Turbulent Flow By Electrochemical Methods, C. Deslouis, I. Epelboin, B. Tribollet, L. Viet

Symposia on Turbulence in Liquids

Mass transfer to the surface of rotating electrodes during turbulent flow was studied by electrochemical methods under steady and non-steady state diffusion conditions.

The flow was due to a large rotating disk made from insulating material, flush with the surface of which was mounted a ring shaped electrode of platinum or nickel.

A local study of the radial component of the convective diffusion in turbulent flow was carried out with very thin ring electrodes (width ΔR ~ 0,05 mm). The diffusion layer thickness was varied relatively to the diffusion sublayer thickness by changing the ring width or the rotation speed …

Experimental Study Of Turbulence In Plane Separated Flows, R. Smyth

Symposia on Turbulence in Liquids

Some recent attempts at predicting turbulent two- dimensional recirculating flows have concentrated on modelling the turbulent energy equations used in the finite difference analysis methods of solutions of the elliptic partial differential equations governing these flows. These attempts have to some extent been restricted by the lack of experimental studies of the high turbulence intensities found in separated flows. The improvement of the pulsed hot-wire anemometer and the laser Doppler anemometer have made possible such studies and this paper describes an investigation using the laser Doppler anemometer in a separated flow situation. Results are given of an experimental study of …

The Roles Of Large Scale Structures In The Initial Development Of Circular Jets, F. K. Browand, J. Laufer

Symposia on Turbulence in Liquids

Experimental results are presented describing the flow field surrounding the potential core of a circular water jet in the Reynolds number region between 5,000 and 15,000. This field is divided into three regions: 1) the shear layer instability zone; 2) the vortex interaction region; and 3) the zone of higher order instability mode and turbulence generation. It is shown that the origin of the large scale structures just downstream of the potential cone can be traced to the upstream vortices, but their statistical behaviour (passage frequency, spatial coherence) seems to be independent of the initial shear layer instability.

Stereoscopic Photography Of Shear Flow Turbulence, A. K. Praturi, H. C. Hershey, R. S. Brodkey

Symposia on Turbulence in Liquids

The last several years have seen numerous advances in the understanding of the coherent motions that exist in turbulent shear flows. These studies have provided the underlying basis of most of the experimental investigations of coherent motions using conditional sampling, quadrant splitting, pattern recognition, etc. Lacking, however, in the visual work is a true three- dimensional view of the processes, which are known to be three-dimensional in nature. Possible means of providing information about the third dimension are reviewed. Details of an evaluation of a stereoscopic-photographic, high-speed motion picture system are given. The system utilizes the boundary layer flow channel …

Intrinsic Viscosity Of Stiff Dumbbells From Time Correlation Functions, Gerald Wilemski

Physics Faculty Research & Creative Works

The intrinsic viscosity of a suspension of stiff dumbbells is evaluated by a time correlation function method. The required moments of the internal coordinates are calculated directly from the diffusion equation, without explicit evaluation of the Green's function. For the rigid dumbbell, the correct high frequency limit is obtained, disposing of recent doubts over this possibility. The interplay of dumbbell stiffness and shearing frequency is also illustrated.

Energy And Angular Distribution Of Electrons Ejected From Helium By Fast Protons And Electrons: Theory And Experiment, Steven Trent Manson, Larry H. Toburen, Don H. Madison, Nikolaus Stolterfoht

Physics Faculty Research & Creative Works

A comprehensive study of the angular and energy distributions of electrons ejected in collisions of fast electrons and protons with He is presented. New experimental results for 300-keV, 1-MeV, and 5-MeV proton impact are reported along with theoretical results for 2-keV electron impact and 100-keV, 300-keV, 1-MeV, and 5-MeV proton impact. The theoretical results, based upon Born approximation with Hartree-Slater initial discrete and final continuum wave functions, show excellent agreement with experimental electron-impact results. Serious discrepancies are found between theory and experiment in the angular distribution of ejected electrons for forward angles for 100- and 300-keV proton impact; the discrepancies …

Some Comments On Correlation-Function Formulas For Polymer Intrinsic Viscosity, Walter H. Stockmayer, Gerald Wilemski, Hiromi Yamakawa, Genzo Tanaka

Physics Faculty Research & Creative Works

No abstract provided.

Binary Nucleation. Ii. Time Lags, Gerald Wilemski

Physics Faculty Research & Creative Works

The role of the time lag needed to attain steady state nucleation in binary vapors is discussed. Under appropriate conditions it is possible to obtain both a large predicted rate of binary nucleation and a large time lag. In this circumstance, homogeneous nucleation of the more concentrated component may be the predominant process. It is of obvious importance to the experimentalist to differentiate between these possibilities. Approximate formulas for the time lags are developed, and representative calculations for the ethanol-water system are reported.

Binary Nucleation. I. Theory Applied To Water-Ethanol Vapors, Gerald Wilemski

Physics Faculty Research & Creative Works

A quantitative study of nucleation in vapor mixtures of ethanol and water near 273°C is presented. First, Reiss' theory of binary nucleation is reexamined. The theory is modified slightly in order to yield the proper limit for homogeneous nucleation in a one-component system. Moreover, a corrected expression for the equilibrium concentration of mixed clusters is derived. Calculations of the critical vapor activities needed to produce a visible condensate are presented and compared with the results of Flood's cloud chamber experiments. The agreement is only fair, but qualitative accord is found.

The Missouri Miner, April 17, 1975

The Missouri Miner Newspaper

No abstract provided.

The Missouri Miner, April 03, 1975

The Missouri Miner Newspaper

No abstract provided.

Load Factors For Wind And Snow Loads For Use In Load Resistance Factor Design Criteria, M. K. Ravindra, Theodore V. Galambos

CCFSS Library (1939 - present)

This report presents the background and the derivations for the determination of the mean maximum loads and the corresponding load factors for wind and snow loading for use in Load and Resistance Factor Design Criteria for steel building structures.