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Front Matter, University Of Missouri--Rolla

Symposia on Turbulence in Liquids

No abstract provided.

The Influence Of Ambiguity And Noise On The Measurement Of Turbulent Spectra By Doppler Scattering, J. L. Lumley, W. K. George, Y. Kobashi

Symposia on Turbulence in Liquids

A fundamental uncertainty in velocity measurement by Doppler scattering is caused by the finite residence time of the scattering particles in the observation volume; the arrival of scattering particles at arbitrary times gives rise to fluctuations in phase (and hence frequency) of the observed Doppler frequency. An estimate is obtained for the spectrum of these frequency fluctuations (called ambiguity noise). The frequency at which the spectral levels of a turbulent signal and the ambiguity noise are equal, provides a limit to the temporal resolution of an instantaneous velocity measurement; this limit is obtained, and shown to be quite restrictive. The …

Laser-Doppler Measurements Of The Decay Of Velocity Fluctuations In Dilute Polymer Solutions, Neil S. Berman, Eugene E. Cooper

Symposia on Turbulence in Liquids

Finite disturbances were generated in a pipe containing water or a 20 ppm solution of Separan AP-30 in water by oscillating a sleeve at the wall. The sleeve amplitude in the axial direction varied from 0.5 to 2.0 inches and the frequency from 0.25 to 1.0 Hz. Downstream of the sleeve oscillations in the fluid velocity were measured with a laser Doppler flowmeter at various axial and radial positions to determine behavior at the lower frequency part of the stability curve for water. The response amplitude, phase angle and the mean velocities were measured for both fluids at Reynolds numbers …

Optical Statistical Measurements Of Free Convection Flow Patterns, E. F. C. Somerscales

Symposia on Turbulence in Liquids

Measurements have been made of the autocorrelation of photographs of the flow patterns produced at high Rayleigh numbers in a horizontal layer of liquid heated from below and cooled on top. The relation of these measurements to temperature measurements in the fluid are considered. Analogous situations in other physical systems are also discussed.

The Use Of Electrochemical Techniques To Study Turbulence Close To A Wall, Kamalesh K. Sirkar, Thomas J. Hanratty

Symposia on Turbulence in Liquids

Electrochemical techniques can be used to measure the time averaged velocity gradient and the two components of the fluctuating velocity gradient at a solid surface. A chemical reaction Is carried out at the surface of a small electrode embedded in the wall. The voltage applied to the electrode Is large enough that the current flowing in the circuit is controlled by the mass transfer rate. The probes are the mass transfer analog of the hot wire or hot film anemometer. If the test electrode is part of a large electrode surface, it can be used to measure local time averaged …

Ultrasonic Study Of Turbulent Water Flow, W. K. Kramer, R. Grosskreutz, A. Dinkelacker

Symposia on Turbulence in Liquids

The propagation of ultrasonic waves through turbulent water flow has been Investigated experimentally. While passing the turbulent region the sound waves are modulated to some extent. The degree of modulation and the frequency spectra of the modulation are closely related to the properties of the flow. It seems to be possible to use this method for turbulence measurements in liquids, whereby the absence of a probe in the flow region and a possibility to differentiate between velocity and density fluctuations would be special advantages. A disadvantage can be the fact that Information is collected on the whole sound path.

Turbulence Measurements In Water, Francois J. Resch

Symposia on Turbulence in Liquids

Turbulence measurements in water have been undertaken using hot film anemometers in a circular conduit. Two different types of film probe were tested and the problem of drift of the calibration curves was carefully studied. A heat transfer law was established for conical hot film probes.

Some turbulence measurements, made at the axis of the pipe, were compared with the corresponding measurements undertaken in air flow. The comparison led to the conclusion that turbulence measurements can be carried out in water with the same degree of accuracy as those carried out in dynamically similar air flow.

Two-Dimensional Laser-Doppler Velocimetry In Turbulent Flows, N. E. Chatterton, R. D. Lewis, E. W. George

Symposia on Turbulence in Liquids

Localized measurement of the velocity of flow In fluids may be accomplished by detecting the Doppler shift In frequency from coherent, monochromatic light scattered from micrometer sized contaminant particles within the flow. The versatility of applications of this technique, first used several years ago, has been expanded by recent research. The basic geometry of measurement, in which the scattered energy is recombined with light energy at the original frequency on the face of the photocathode of a photomultiplier tube, can be rearranged in many alternative configurations to meet the needs of the experimenter. By using a single laser, additional arrangements …

Turbulence Measurements In Shear Flow Liquid Systems, Robert S. Brodkey, M. F. Cohen, J. S. Knox, G. L. Mckee

Symposia on Turbulence in Liquids

The paper is a composite of a number of years of work on turbulence measurements in a variety of liquid flow systems. The trials and tribulations of such measurements are emphasized. Pipe flow Is considered in some detail, and the consistency between results of various investigators is analyzed. Other systems discussed are a stirred tank unit and a multi-jet reactor configuration. Statistical turbulence measurements such as autocorrelation, spectrum, probability density, flatness factor, and skewness factor are considered in terms of obtaining these from digital signals obtained by conversion of the normal analog signals. Descriptive parameters of statistical turbulence, such as …

Bibliography Of Hot-Wire-Film Anemometry In Liquids, R. L. Humphrey

Symposia on Turbulence in Liquids

It is not a new idea to use heat transfer from a hot sensor in a fluid stream to measure velocity and turbulence. This was done as long ago as 1909 by Mr. Kenelly, but a systematic study was not followed through until 1914 by L. V. King. After this followed a series of dedicated people, some students, some professors, some scientists, who continually advanced the state of the art of anemometry in liquids. This paper deals with their work in the areas of electronics (integrated circuits) and physics (thin film technology), and shows how, in time, these two areas …

Some Basic Properties Of Low Quality Two-Phase Turbulent Flow, G. Hetsroni, S. Einav

Symposia on Turbulence in Liquids

This Is an exploratory study dealing with the effect of gas bubbles on the turbulence Intensity of the liquid in a two-phase flow.

Distributions of time-mean and fluctuating velocities were measured in a two - dimensional channel. These were measured for single-phase flow and on the two sides of a bubble layer, which simulated the two-phase flow.

In single-phase flow the distribution of the time-mean velocities agrees well with other data, while the distribution of the Intensity of turbulence Is lower than expected.

The measurements of the time-mean velocity and turbulence Intensity across the bubble layer revealed that they are …

Turbulence Measurements In Stably Stratified Fluids, Yih-Ho Pao

Symposia on Turbulence in Liquids

A towing tank system was used to study the structure of turbulence in stably stratified fluids. Turbulence is generated by moving an obstacle (a grid or a cylinder) in a tank of stratified salt water. Recent improved shadowgraph pictures of these laboratory generated stratified flows are shown in this paper. They give further support to Pao's observation that (i) internal waves and turbulence coexist in turbulent stratified flows, with internal waves at the large scales and turbulence at the small scales; (ii) turbulence decays much more rapidly than internal waves; and (iii) the turbulent-nonturbulent interfaces are not necessarily sharp, and …

The Response Of A Hot-Wire Anemometer To A Bubble Of Air In Water, S. C. Chuang, V. W. Goldschmidt

Symposia on Turbulence in Liquids

The sensitivity of peak voltage drop and duration of the change In sensor voltages due to the impaction of different size bubbles are confuted and measured. Excellent agreement between these is found for bubbles somewhat larger than the sensor diameter and smaller than Its effective length in water streams in a range of 1.5 to 9 feet per second. The method suggests a reliable method for sizing bubbles in a water stream. The effects due to nondirect hits are not treated.

Experimental Investigation Of Polymer Solution Injection On External Boundary Layers, Brian Latto, Chi-Hung Shen

Symposia on Turbulence in Liquids

This paper describes an experimental study of the effects of injecting dilute aqueous polymer solutions into a turbulent boundary layer formed on a flat plate immersed in flowing water.

Hot-film anemometer techniques were employed in the measurement of the velocity profiles, turbulence intensities, and lateral correlation coefficients at a number of locations along the plate. Boundary layer growth parameters and the variation of the local skin friction coefficient were computed from the velocity profile data. The effects of polymer concentration and injection velocity on the local drag reduction are also presented.

It was found that momentum diffusivity was smaller than …

Turbulence Measurements In Dilute Polymer Flows, Joseph M. Wetzel, John A. Almo, John M. Killen

Symposia on Turbulence in Liquids

A hot-film sensor was flush-mounted in the wall of a four-inch pipe and was calibrated as a function of wall shear stress. Flows with water and with homogeneous aqueous solutions of Polyox WSR-301 were utilized. The heat transfer characteristics of the sensor were reduced for polymer flows. Measurements of the number of zeroes and the frequency spectra for the turbulent fluctuations were obtained for a variety of test conditions. The effects of Polyox WSR-301 on surface pressure fluctuations on both smooth and rough surfaces were also measured.

Some Aspects Of Flow Through Rotating Circular Tubes, D. L. Boyer, J. R. Guala

Symposia on Turbulence in Liquids

The flow of water in a circular tube rotating about an axis perpendicular to the axis of the tube is studied. Information about the flow is obtained from coated hot-film probes and a constant temperature anemometer. A maximum Reynold's number of 9,500 is obtained and the Taylor number is varied from 800 to 3,100. Little similarity is found to exist between flows in rotating and in non-rotating systems in this range of parameters.

An Experimental Facility For The Visual Study Of Turbulent Flows, Robert S. Brodkey, Harry C. Hershey, Edward R. Corino

Symposia on Turbulence in Liquids

An experimental technique which allows visual observations of the wall area in turbulent pipe flow is described in detail. It requires neither the introduction of any injection or measuring device into the flow nor the presence of a two-phase flow or of a non-Newtonian fluid. The technique involves suspending solid MgO particles of colloidal size in trichloroethylene and photographing their motions near the wall with a high speed movie camera moving with the flow. Trichloroethylene was chosen in order to eliminate the index of refraction problem in a curved wall.

Evaluation of the technique including a discussion of limitations is …

Experimental Investigation Of The Hydrodynamic Stability Of Flow In Rotating Pipes Using Thermistors, Hassan M. Nagib, Ludwig Wolf Jr.

Symposia on Turbulence in Liquids

The hydrodynamic stability of flow in a rotating pipe Is investigated experimentally using thermistors. The experimental apparatus consists of a rotating pipe made of lucite, 3-1/4 inch inside diameter, six feet long, equipped with porous plugs at the ends to minimize recirculation. The working fluid is water and a range of axial and tangential Reynolds numbers up to 7,000 and 20,000, respectively, is covered. Thermistors were chosen for this study since their high electrical resistivity yields strong signals which permit the use of inexpensive and convenient electronics. They also have a high temperature coefficient of electrical resistance which minimizes the …

The Structure Of A Turbulent Water Jet, Philip J. Morris

Symposia on Turbulence in Liquids

Experimental studies are made to determine the structure of a turbulent water jet.

The paper is divided into two parts. The first gives practical information about the techniques and instrumentation developed to make measurements with hot-wire anemometers in water. A short theoretical discussion is given on the dynamic response of heated fibre in liquids. The second part reports on the results obtained in a one-inch water jet at Reynolds numbers between 12,000 and 20,000. Mean axial velocity measurements are made in the initial five diameters of the jet and the results are used to predict the nature of the vortex …

Author Index, University Of Missouri--Rolla

Symposia on Turbulence in Liquids

No abstract provided.

Diffusion Coefficients Over Rough And Smooth Boundaries, Obtained By Measuring The Concentration-Velocity Covariance, R. S. Mcquivey, T. N. Keefer

Symposia on Turbulence in Liquids

A preliminary investigation of the coefficients of turbulent diffusion in an open channel was conducted by employing: 1) hot-film anemometry to detect the velocity fluctuation, 2) a platinized single-electrode conductivity probe to detect the concentration fluctuations, and 3) a digital computing system to evaluate the covariance and other statistical properties of the two output signals.

Data were collected downstream of a constant-discharge point source of neutrally-bouyant salt solution at stream temperature and velocity. Using current semi-empirical methods diffusion coefficients were obtained in the vertical and lateral directions as well as dispersion coefficients due to convection.

Use Of A Constant Temperature Hot-Wire Anemometer To Compensate For The Thermal Lag, Peter Freymuth

Symposia on Turbulence in Liquids

A constant temperature hot-wire anemometer can be used to compensate for the thermal lag of a wire or film resistance thermometer within the useful frequency range of the anemometer. This method may be used as an alternative to the standard method in which a differentiation circuit as employed in constant current anemometers is used for frequency compensation. The new method is useful if a constant temperature anemometer is at hand. The time constant of the resistance thermometer need not be determined.

Measurements Of Turbulence Characteristics In Water And In Dilute Polymer Solutions, Tadeusz Kowalski

Symposia on Turbulence in Liquids

Measurements of turbulence characteristics were made inside a boundary layer in external flow of water and in water with polymer additives of the Polyox type. Flush mounted hot-film sensors and wedge, parabolic, and cylindrical sensors were used to measure the turbulent velocity fluctuations. Graphs are given of energy density, dissipation, turbulence shear correlation spectra, and microscale of turbulence distribution. Tests were run in an open channel flow at one Reynolds number and two rates of polymer injection to give 20 and 40 ppm average concentration in the boundary layer. The results indicate that the advent of the quartz insulated hot-film …

Frequency Response Studies For A Wedge Probe In Viscoelastic Fluids, J. M. Rodriguez, Gary Kent Patterson, J. L. Zakin

Symposia on Turbulence in Liquids

The response of a hot-film wedge probe in viscoelastic fluids has been investigated by imposing on the probe a sinusoidal vibration of known amplitude and frequency. Root-mean-square (rms) velocities calculated from the displacement of the probe were compared to rms velocities obtained with a constant temperature anemometer. The tests were performed under turbulent flow conditions and also at flow rates where viscoelastic effects (i.e., decrease of heat transfer rates from the probe to the fluid and drag reduction) were observed.

The frequency range covered was narrow ( < 100 cps). This limitation was imposed by the decision to superimpose the sinusoidal vibrations on the turbulence signal, in order to have dynamic conditions similar to those encountered in actual turbulence measurements. Measurements were performed in mineral oil and four solutions of polyisobutylene (Vistanex L-200) In mineral oil.

The experimental technique was established by measuring the response of the probe in …

A Simple Observational Technique For The Investigation Of Boundary Layer Stability And Turbulence, Tony Maxworthy

Symposia on Turbulence in Liquids

A dense suspension of aluminum flakes in a fluid has many advantages as a flow-visualization method, and has been used to study circular Couette flow and Benard instability, among others. In the present contribution the scientific and pedagogical merits of the technique are examined further for three different cases: (a) Stability of Poiseuille flow; (b) Stability of the side-wall boundary layers created when a fluid-filLed, rotating container is suddenly brought to rest; (b) Stability of the boundary layer beneath a concentrated vortex.

The technique is also useful in other cases, especially when fundamentals of fluid flow are to be demonstrated …

Measurements Of Density Fluctuations In Submerged Water Jets, L. N. Wilson, D. W. Prosser

Symposia on Turbulence in Liquids

A remote sensing technique, free from many of the problems associated with Inserting probes into a liquid flow, has been developed to measure turbulent density fluctuations In a low speed, submerged water jet. The technique employs two schlieren optical systems, composed of He-Ne lasers and photo detectors. The optical beams intersect in the flow in a plane perpendicular to the flow direction. Knife edges are aligned such that the systems are sensitive to gradients of refractive index in the flow direction. An analysis is presented which relates the cross-covariance of the two signals to the local two-point refractive-index covariance and …

Effect Of Dilute Polymer Solutions On External Boundary Layers, Brian Latto, J. A. Middleton

Symposia on Turbulence in Liquids

The paper reports an experimental study of the flow of homogeneous aqueous polyacrylamide MRL 402 solution over a thin flat plate. Extensive velocity profile data were obtained, using both cylindrical and conical hot-file probes, and used to obtain local skin friction profiles. Direct drag measurements were made over a period of time for concentrations of 0, 25, 50 and 75 wppm and indicated that there was no appreciable degradation of the polymer. Extensive turbulence intensity data were obtained which were contradictory but indicated that the conical type probe is better than the cylindrical type for turbulence measurements and that the …

Conference Proceedings Of The Symposium On Turbulence Measurements In Liquids, September 1969, University Of Missouri--Rolla

Symposia on Turbulence in Liquids

No abstract provided.