Engineering Commons^™

Simultaneous Measurement Of Longitudinal Velocity And Temperature Fluctuations With A Single Wire In Non-Isothermal Flow, P. J. Mcconachie, K. J. Bullock

Symposia on Turbulence in Liquids

A method for measuring longitudinal velocity and temperature fluctuations with a single wire probe is presented and the principles of operation verified by an analog computer solution of the finite hot wire, anemometer control and signal processor equations. Examination of the basic equations reveals that such a probe is best suited to the study of turbulent water flows, thus allowing high Reynolds numbers to be attained without limitations on frequency response. Inherent sources of error are investigated and the method shown to be reliant mainly on the initial accuracy of wire calibration.

Front Matter, University Of Missouri--Rolla

Symposia on Turbulence in Liquids

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.

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 …

Unidimensional Turbulence In A Sheet Flow Under Rainfall - A Stochastic Analysis, H. L. Shahabian, A. Giorgini, J. W. Delleur, A. R. Rao

Symposia on Turbulence in Liquids

Probability distributions of longitudinal velocity fluctuations are presented for cases with and without rainfall. They deviate from the normal distribution. These velocity fluctuations are fitted by an autoregressive - moving average process. The process explains adequately the variance of the series.

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.

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.

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 …

Red Blood Cells And Turbulence, E. F. Blick, H. N. Sabban, P. D. Stein

Symposia on Turbulence in Liquids

Measurements were made of the turbulence intensity of blood of various hematocrits (volume percentage of red cells in blood) flowing through an orifice. The maximum relative turbulence intensity was found to occur in the hematocrit range of 20% - 30%.

The Influence Of Suction On Energy Distribution In Fully Established Turbulent Pipe Flow, M. Schildknecht, J. A. Miller, G. E. A. Meier

Symposia on Turbulence in Liquids

The influence of suction on the structure of turbulence in fully established pipe flow has been experimentally investigated. Extensive hot-wire measurements indicate major alterations in the turbulent energy distribution, particularly in the wall layers result from mild suction rates, less than 5 percent of the mean mass flow.

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.

Session Chairman Introductory Remarks, R. J. Hansen

Symposia on Turbulence in Liquids

No abstract provided.

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.

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.

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