Turbulence Structure for Fully Developed Flow in Rough Pipes

Powe, R. E.; Townes, H. W.

doi:10.1115/1.3447010

Cited by 12 publications

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“…However, since for single and X-hot-film probes the u-velocity component is contaminated by the velocity components not measured, it is impossible to conclude from these tests which of the results are best in the region close to the wall. Figure 11 b compares the rms velocity of the present study with that of Morrison and Kronauer (1969), Powe (1971), Lawn (1971), and Perry and Abell (1975. All these data agree reasonably well far away from the wall.…”

Section: Vector Measurements In Turbulent Pipe Flowmentioning

confidence: 64%

Measurement of velocity vectors with orthogonal and non-orthogonal triple-sensor probes

Lekakis

Adrian

Jones

1989

Experiments in Fluids

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Abstract.A new method of interpreting the signals from triplesensor thermal anemometer probes has been developed based on fast solution for all the roots of the non-linear Jorgensen (1971) equations describing the directional response of each cylindrical sensor. The sensors can be oriented at arbitrary angles to each other, but always within a range of probe geometries that keep prong interference and thermal wake interference below acceptable levels. The properties of a class of non-orthogonal symmetric tetrahedral probe geometries are studied in relation to the range of flow vector angles that can be measured, the sensitivity of the probe with respect to changes in flow angle, and the sensitivity of the computed velocity components due to angular errors associated with the construction of the probe. The solutions of Jorgensen's equations are inherently multiple-valued, but if the velocity vector is restricted to be within a cone of angles, they are unique. It is shown that measurements with non-orthogonal triple sensor signals are sensitive to angular deviations of a few degrees of the sensor angles from the nominally orthogonal probe geometry, indicating the need of a non-orthogonal algorithm. The mean, rms, Reynolds stress, and power spectrum of the velocity in fully developed turbulent pipe flow were measured using a specially designed triple sensor probe and the proposed algorithm.

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Section: Vector Measurements In Turbulent Pipe Flowmentioning

confidence: 64%

Measurement of velocity vectors with orthogonal and non-orthogonal triple-sensor probes

Lekakis

Adrian

Jones

1989

Experiments in Fluids

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“…Combining this with equation 5and either equation 1or equation 2gives the type of experimental results to be expected from different types of mixers. For a mixer which imparts large shear deformations with no reorientation of interfaces, one would expect ja(uM r /g)' w (7) while for a mixer with N shearing sections and reorientation of fluid interfaces between sections one would expect…”

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confidence: 99%

Discussion: “Vortex Motions Induced by V-Groove Rotating Cylinders and Their Effect on Mixing Performance” (Rotz, C. A., and Suh, N. P., 1979, ASME J. Fluids Eng., 100, pp. 186–192)

Tucker

1980

Journal of Fluids Engineering

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axis. This assumption, however, will be available only in the upstream region in the rotating pipe, and in the far downstream region where the flow is in a fully developed state, the assumption will not be valid. As is seen in the velocity profiles at the sections of l/D > 100 in the rotating pipe, where a fully developed flow is almost established, a velocity profile different from a solid body rotation type is maintained in the circumferential component. In this case, it may be considered that a tangential stress will be present between fluid layers and hence, some energy must be supplied to the flow by the rotating pipe wall. The preservation of this concave velocity profile in the tangential component will allude to an existence of a longitudinal vortices in the rotating pipe. Cannon and Kays have observed them in the mid-radius region of the rotating pipe. Detailed measurements of the turbulence in the rotating pipe are now being prepared. Vortex Motions Induced by V-Groove Rotating Cylinders and Their Effect on Mixing Performance 1 C. L. Tucker. 2 The authors are to be congratulated for taking on a difficult task, that of correlating fluid mechanics and mixing in a complex flow geometry, and for doing an excellent job. It has long been the goal of workers in this field to predict the performance of mixing devices without resorting to empiricism, and this paper marks an important advance towards that goal. In their introduction, the authors state that one question they hoped to answer was "whether the effect of the grooves was to increase the total amount of shear deformation imparted' to the fluids or to overcome the adverse effects of interface orientation." This is a critical question, for if interface orientation effects can be overcome, it should be possible to create laminar mixers which are orders of magnitude more efficient than conventional devices. For example, Erwin [1] has pointed out that so-called mixing sections in single screw extruders increase mixing efficiency by reorienting fluid interfaces with respect to the shear deformation in the rest of the extruder. The authors conclude their paper by stating that V-grooved cylinders enhance mixing primarily by providing increased deformation, but that interface reorientation may be present as well. Since the time when this work was done, some progress has been made in mixing theory and in relating experimental measures of mixing to the type of measures usually employed by theoreticians. When the experimental evidence in this paper is examined in the light of these developments, I believe it is possible to show that there are no reorientation effects present in these particular mixers, and that as a result, the efficiency of V-grooved mixers must be due to increased deformation. First, assume that the degree of mixing imparted to the fluid can be characterized by a striation thickness, X. Laminar mixers tend to produce layered mixtures, and the striation thickness is simply the thickness of the repeating unit in a regularly layered mixture [2]. Whe...

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Use of the equation for turbulent viscosity to describe the flow near a rough surface

Лебедев¹,

Sekundov²

1976

Fluid Dyn

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Turbulence Structure for Fully Developed Flow in Rough Pipes

Cited by 12 publications

References 0 publications

Measurement of velocity vectors with orthogonal and non-orthogonal triple-sensor probes

Measurement of velocity vectors with orthogonal and non-orthogonal triple-sensor probes

Discussion: “Vortex Motions Induced by V-Groove Rotating Cylinders and Their Effect on Mixing Performance” (Rotz, C. A., and Suh, N. P., 1979, ASME J. Fluids Eng., 100, pp. 186–192)

Use of the equation for turbulent viscosity to describe the flow near a rough surface

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