Electrokinetic-potential fluctuations produced by pipe-flow turbulence

CER62HC-JEC47.July 1964.The distribution across a pipe of turbulent intensities, shearing stress, and energy spectra are inferred from measured electrokinetic-potential fluctuations in a fully developed flow of distilled water in a 2.54 cm diameter glass pipe. These quantities are shown to be in good agreement with those obtained by Laufer and Sandborn with hot-wire anemometers for air flows at the same mean Reynolds number. A tentative analytical model of the phenomena is constructed and analyzed by Maxwell's electrodynamic field equations for a nonmagnetized medium moving with a velocity which is much smaller than the velocity of light. A set of equations governing the interrelation between the electrokinetic- potential fluctuations and the turbulent velocity-fluctuation components of the flow field in fully developed pipe flow is deduced. The equations are simplified and assumed to have the form: σ▽ѱ = ρu. Fourier transforms are then introduced and simple relations between the electrokinetic-potential fluctuations and velocity fluctuations are obtained

Wind-tunnel study of diffusion and deposition of particles with appreciable settling velocities: annual report

CER84-85MP-JEC48.Includes bibliographical references (page 45).May 1985.Project No. 5-32512.Prepared for Department of the Army, U.S. Army Armament Research and Development Command, Chemical Systems Laboratory, Aberdeen Proving Ground.The deposition on a smooth surface of particles with appreciable settling velocities Vg and small Froude numbers Vg2/gh, where h is the height of the source in a neutrally stable boundary layer, was studied in a meteorological wind tunnel. The measured longitudinal deposition rates of the deposited particles were closely predicted by an approximate model, which relates the deposition rate of settling particle plumes to the diffusion of passive plumes with no reflection from the ground. The lateral dispersion rates of the settling particle plumes were found, however, to be smaller than those of passive plumes

Wind-tunnel study of America's Tower, Dallas

CER81-82JAP-JEC57.Includes bibliographical references (page 25).April 1982.CSU Project 2-27960.For Harwood K. Smith & Partners

Wind-tunnel study of Manhattan Place, New York City

CER83-84JAP-JEC23.Includes bibliographical references (page 23).December 1983.CSU Project 2-95620.For Environmental Science & Services Corp

Atmospheric transport of hydrogen sulfide from proposed geothermal power plant (unit 18): predictions by physical modeling in a wind tunnel

CER77-78JEC-RLP3.Prepared for Pacific Gas and Electric Company.September 1977.Tests were conducted in the Colorado State University environmental wind tunnel facility of the transport and dispersion of the H2S plume emanating from a cooling tower (Unit 18) positioned at two locations near Anderson Springs, California. The wind tunnel tests were conducted with a cooling tower and terrain modeled to a scale of 1:1920. The effects of wind direction and wind speed upon the groundlevel H2S concentrations in the vicinity of Anderson Springs were established. Data obtained include photographs and motion pictures of smoke plume trajectories and ground-level tracer gas concentrations downwind of the cooling tower

Turbulence induced changes in vortex shedding from a circular cylinder

CER73-74KMB-JEC27.Includes bibliographical references (pages 61-66).Prepared under Office of Naval Research contract no. N00014-68-A-0493-0001; project no. NR 062-414/6-6-68 (Code 438).January 1974.Turbulence effects on vortex shedding from a circular cylinder were investigated in a wind tunnel. Most of the literature on vortex shedding reports investigations in air flows where special efforts had been made to keep the turbulence intensity very low (usually <.5%) in the free stream. Under such conditions, vortex shedding from a circular cylinder can be classified into four regimes with a discontinuity condition between each two succeeding regimes. These regimes are identified by the span of Reynolds numbers, Re, and Strouhal numbers, St, by the angle of boundary layer transition, α, and by the transition point from laminar to turbulent flow in the boundary layer or vortex. In this study, turbulence intensity, near the center of a wind tunnel, was increased from .3% to 25% by plates of similar geometry (many small holes) with blockage ratios from .50 to .97. The Re of all flows was kept near 4 x 104. Vortex shedding frequency, f, was observed simultaneously by a pressure transducer (with sensors on cylinder surface) and a hot wire anemometer (immediately downstream). Means of 50 to 150 cross-spectra defined f. Flow visualization, spectra and transducer output voltages with different α were utilized to estimate transition and separation. Four concepts were verified that are already in the literature. As the turbulence intensity of the upstream flow is increased: (a) the vortex shedding regimes occur at lower Re; (b) discontinuities lose any dominant f value that they might have had; (c) vortices are destroyed closer to the cylinder; and (d) the size of cylinders influence turbulence effects on vortex shedding. Six things were observed that have not been published, to the best of the author's knowledge: (a) analogous changes in vortex shedding processes can be obtained either by increasing the air speed (while holding the turbulence intensity very low) or by increasing the turbulence intensity (while holding the air speed approximately constant); (b) the frequency of the vortex shedding becomes relatively smaller, for the vortex shedding regime, as the turbulence intensity is increased; (c) an estimate of the turbulence induced changes in vortex shedding can be made from Re of the flow, mean air speed, rms value of longitudinal speed fluctuations, integral scale of turbulence and cylinder diameter; (d) the "super critical" regime , associated with highest α and St, can be disrupted by sufficient turbulence intensity; (e) the extent to which turbulence can induce changes in vortex shedding is limited. A model of vortex shedding is hypothesized which includes the concept that vortex shedding is continuous from Re near 40 until either the mean air speed and the turbulence intensity, or both, are increased until turbulence destroys individual vortices before they can be shed

Wind-tunnel study of United Bank Center Winter Garden, Denver

CER83-84JAP-JEC24.For United Bank of Denver through Gerald D. Hines Interests.Includes bibliographical references (page 24).December 1983

Diabatic wind and temperature profiles, The

CER69-70HC-JEC-18.December 1969.Includes bibliographical references (page 13).Prepared for U.S. Army Research Grant DA-AMC-28-043-65-G20.KEYPS model and Monin-Obukhov's log-linear model were examined pertaining to their adequacy of describing wind and temperature profiles in thermally stratified shear flows for diversified thermal stability. The dimensionless wind shear and lapse rate for all ranges of thermal stability studied, - 2 .0 ≤ Ri ≤ 0.4, were shown to be linearly dependent on the dimensionless height derived from the log-linear model. Deacon numbers behaved quite differently from what were predicted by KEYPS model.Under grant DA-AMC-28-043-65-G20

Turbulent flow over a wavy boundary

CER71-72PSB-JEC44.Includes bibliographical references (pages 53-57).May 1972.An experimental study was made of turbulent flow over a wavy surface. Sinusoidal waves of three sizes were used to explore the variations of flow with wave size. Measurements of mean and turbulent velocities were taken with a two-wire method. Local heat transfer rates and pressures on the wavy surface were also measured. An equilibrium turbulent boundary layer, which conforms to Rotta's and Clauser's self-preservation requirements, develops in the region far downstream from the first wave. In the lower portion of this layer, the mean velocity is represented by the logarithmic velocity profile when the form-drag measurements of skin friction are used to determine the shift-in-origin. The roughness function is related to the wave height since the wavy surface is shown to be a "k" type surface. The velocity defect profile in the logarithmic form extends to higher values of yu*/ϐ*U∞ than those for smooth wall flows. Eddy viscosity results support the assumed logarithmic velocity variation in the lower part of the boundary layer. Measurements of shear stress by either the two-wire or the heated-film method disagree with the form drag measurements of skin friction. The wavy surface is an extended surface windbreak since it reduces the overall wind speed above the surface and creates vortices between the waves. However, surface shear stresses are increased, and the erosion rate of field waves is a function of wave height.U.S. Department of Interior, Office of Water Resources Research, Contract No. 14-01-0001, U.S. Department of Defense, Office of Naval Research, Contract No. N00014-68-A-0493-0001

Wind-tunnel study of Pet Plaza, St. Louis: wind pressures on glass wall

CER84-85JAP-JEC19.Includes bibliographical references (page 11).November 1984.CSU Project 2-95950.For Kuhlmann Design Group, Inc