Engineering Commons^™

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.

Spatial Filtering In Laser Anemometry, L. Lading

Symposia on Turbulence in Liquids

The concept of spatial filtering is treated in relation to laser anemometry. The basic techniques are analyzed. Recommendations for specific set-ups are given.

Measurement Of Turbulence Power Spectra In Agitated Vessels Of Different Size With A Laser-Doppler Velocimeter, K. Van Der Molen, H. R. E Van Maanen

Symposia on Turbulence in Liquids

We have used the laser-Doppler velocimeter with a new noise reduction technique for measurements in water-filled, turbine-agitated vessels of several sizes, but of the same geometry. Mean velocities, turbulence intensities and turbulence power spectra were obtained in the impeller stream region.

With these results we hope, in the future, to put scaling rules for mixing vessels on a sounder basis.

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.

An Investigation Of The Criteria Controlling Sustained Self-Excited Oscillations Of Cylinders In Flowing Water, R. King

Symposia on Turbulence in Liquids

In this paper, water channel experimental data are discussed and compared with conventional wind-tunnel data. Stability criteria are proposed for the cross-flow and flow directions of oscillation. Fluctuating drag force coefficients are deduced from a linear mathematical representation of the cylinder located in flowing water and oscillating in the flow direction.

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.

Flow Visualization Studies Of Check Valve Vibrations, D. S. Weaver, F. A. Adubi

Symposia on Turbulence in Liquids

A swing-type hydraulic check valve was found to vibrate continuously when a damper was applied to prevent slamming. A research program was conducted to develop an understanding of the phenomenon and thereby determine a method of alleviation. This paper describes the flow phenomena observed during flow visualization studies of a two dimensional full scale model of the valve. Such observations give insight into the mechanism of vibration.

Session Chairman Introductory Remarks, T. J. Hanratty

Symposia on Turbulence in Liquids

No abstract provided.

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 …

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.

Separation Of Low Reynolds Number Flows Around A Corner, T. Matsui, M. Hiramatsu, M. Hanaki

Symposia on Turbulence in Liquids

It was shown experimentally that low Reynolds number flows around a sharp corner do not separate at the corner, and separation points move downstream from the corner with decrease in Reynolds number. For the flow in a channel with a backward-facing step, the experimental results showed a good agreement with those of numerical calculation for the position of separation points and the length of standing vortices.

Some Observations Of Wake Behavior In Laminar And Turbulence Free Stream Flow, L. E. Seeley, R. L. Hummel, J. W. Smith

Symposia on Turbulence in Liquids

Visual observations of the sphere wake have been obtained using the flash photolysis technique. Free stream turbulence of 7 and 10% was found to progressively reduce the size of the wake but no turbulence was found in the attached shear layer nor was the position of the separation point affected. A separation bubble was identified as predicted by Son and Hanratty (1969). Evidence is presented to show that drag reduction in turbulent free streams is not due to turbulence in the attached boundary layer but to enhanced momentum transfer in the wake.

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 …

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 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.

Structure Of The Viscous Sublayer In Drag Reducing Channel Flows, W. G. Tiederman, A. J. Smith, D. K. Oldaker

Symposia on Turbulence in Liquids

The objective of this study was to experimentally determine the effect of dilute, long-chain, polymer solutions upon the flow processes in a fully developed, two-dimensional turbulent channel flow. This was accomplished by making motion pictures of dye seeped through a slot into the viscous sublayer. The motion pictures were analyzed to determine the span-wise spacing and the bursting rate of the low-speed streaks that are characteristic of the sublayer structure

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.

Turbulent Pressure Spectrum Measurements On A Compliant Surface, R. N. Brown

Symposia on Turbulence in Liquids

Experimental results obtained by measuring the drag, wall pressure fluctuations, and radiated sound from a compliantly coated cylinder, 21 inches in diameter, and rotating in water are described. The compliant layer was a 1/4-inch thick closed cell, air-filled neoprene which was mounted on the 3/8-inch thick aluminum cylinder walls. Results are presented for four speed conditions; one condition is below the speed where a sudden increase in drag is obtained, and the other speed conditions are at and above this critical speed. In general, the results indicate a surface which becomes increasingly more roughened as the critical speed is exceeded.

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 …

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 …

Computer Program For Binary Distillation Using The Method Of Pochon-Savarit With Enthalpy Data Calculated By Lagrange Interpolation, Joseph J. Rogus

Theses

This thesis presents a Fortran Computer Program to solve binary distillation problems. The solution is obtained by the method of Pochon-Savarit which is based upon graphical use of an enthalpy-concentration diagram. The enthalpy data in this program is calculated using Lagrange interpolation. This is accomplished by utilizing the Lagrange interpolation to get values for the enthalpy of the vapor until we find that value which lies on the same line as the enthalpy of the liquid from the preceding tray and its corresponding del point.

The required input data consist of liquid-vapor equilibrium data, heat of solution data with the …

The Synthesis Of New Maleimide Addition Polymer Precursors, Richard B. Brown

Chemistry & Biochemistry Theses & Dissertations

1H-2,3-dimethylpyrrolo(1,2-a) benzimidazol-l-one (27) and 1H,9H- 2,3,7,8-tetramethyl-bispyrrolo(1,2-a:6,7-a')benzodiimidazo1-1,9-dione (32) have been synthesized from dimethylmaleic anhydride and o-phenylenediamine and 1,2,4,5-tetraaminobenzene, respectively. The presence of reactive olefinic double bonds in the synthesized compounds was of interest as a site for possible addition polymerization.

The synthetic route involved, in both cases, a simple nucleophilic substitution reaction between the diamine(or tetraamine) and the anhydride to form an intermediate amide-acid-amine which rapidly cyclized to the imide amine. The final ring closure required more rigorous conditions and occurred at melt reaction temperatures.

The Thermodynamics Of Electrolytic Solutions, Eric Robert Bixon

Theses

The thermodynamic properties of solutions of electrolytes may be accurately determined by the measurement of the activity of the s6lvent. when the. solute is nonvolatile, this quantity may be obtained from measurements of the lowering of the vapor pressure caused by the presence of the dissolved solute.

An experimental method has been devised to measure this effect using a semi-conventional Othmer Still. The experimental apparatus has been constructed. and evaluated. Data has been-obtained for the vapor pressure lowering of methanol due to the presence of dissolved electrolyte for five different electrolyte-methanol systems. An extrapolation technique was developed to make use …

A Preliminary Study Of The Thermodynamic Limitations Of The Nrtl/Lemf Equations, Robert Petrie

Theses

Analytical evaluations of the second and third derivatives of the molar Gibbs energy of mixing for the NRTL/LEMF equations indicate distinct zones of miscible and inmiscible prediction.

These calculations for a number of different α's have produced approximate miscibility limits for both NRTL/LEMF energy parameters and infinite dilution activity coefficients of a given system.

Transient Phenomena Of Polymer Solutions, Nikolaus Zwetkow

Theses

With the aid of a rotational viscometer, several transient phenomena were studied with different polymer solutions. In order to be acquainted with the operations of the rotational viscometer, viscosity measurements were made on polystyrene solution of a 7.14 wt. % NBS-2-35967 in a 35 - 65 mixture of aroclor and TCP, polyisobutylene (16.5% in mineral spirits), Indopol H-1900 (polyisobutylene) and 4.5% polyisobutylene in Primol 355. All these were done at a temperature of 77°F, except for Indopol H-1900 which was done at different temperatures. The results are listed in the section of tables and graphs.

Viscosity was measured with a …

The Thermal Dehydration Of Magnesium Sulfate Hexahydrate (Mgso3.6h2o) And Magnesium Sulfite Trihydrate (Mgso3.3h2o), Raafat F. Abdel-Malek

Theses

The thermal dehydration of MgSO₃.3H₂O and MgSO₃.6H₂O have been studied by differential thermal analysis, differential scanning calorimetry and thermal gravimetric analysis.

Similar studies by other groups led to contradictory conclusions. In this investigation, these results were reconciled and it was concluded that MgSO₃.6H₂O, under equilibrium conditions, dehydrates in two steps through the intermediate formation of MgSO₃.3H₂O.

One consequence of this work is the development of a simple analytical procedure, using TGA, for the quantitative determination of both hydrates in mixtures and in the presence …

Separation Of Isomers Via Thermal Parametric Pumping, Vincent J. D'Emidio

Theses

Continuous and semicontinuous thermal parametric pumps for separating isomers were experimentally investigated using the model system glucose-fructose-water on a cation exchange resin adsorbent. A comparison was made between the experimental data and the calculated results by a method based on an equilibrium theory. The method invokes the assumptions that a multicomponent mixture contains a series of pseudo binary systems. Each binary system consists of one of the solutes as one component and the common inert solvent as the other component. It has been shown that under certain conditions, the pump with feed at the enriched end has the capacity for …

Use Of Sodium Chloride Windows In The Infrared Spectral Analyses Of Irradiated Thin Insoluble Polymer Films, W. F. Oberbeck, Kenneth G. Mayhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

No abstract provided.

A Kinetic Study Of Lysine And Lysine Derivatives, Stephen Joseph Stanley

Theses

The kinetics of the reaction of iodoacetamide with lysine, polylysine, N-α-Acetyl lysine, and N-ε-Acetyl lysine, have been studied. The investigation was done at 23° C ± 123° C, as a function of pH, and concentration. In all cases it was noted that the rate of reaction increased as the pH increased. The rate data was analyzed in order to obtain the second order rate constants. In addition, the effects of the reactive site's environment on the rate was demonstrated.

Steady State Heat Transfer From A Double Ring Of Identical Spheres In A Regular Orientation, Evelio A. Melo

Theses

Solutions to Laplace's equation are obtained by the method of reflections for the problem of heat transfer from two parallel rings of spheres arranged in regular polygonal arrays. The mathematical models developed describe the rate of heat transfer and spatial temperature distribution due to an arbitrary number of identical spheres of equal surface temperature correcting Fourier's heat transfer equation for the interference caused by a multiparticle array. Although the method of solution is quite rigorous and can be used to obtain as accurate a solution as desired, only the second reflection was obtained, yielding a first order correction. The model …