Pressure and Velocity Distributions in Pulsating Turbulent Pipe Flow Part 2 Experimental Investigations

Ohmi, Munekazu; Usui, Tateo; Tanaka, Osami; Toyama, Masao

doi:10.1299/jsme1958.19.951

Cited by 12 publications

(3 citation statements)

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“…Since the effects of oscillation are confined to smaller regions and also effects on time-mean velocity and wall shear stress are generally of the order of only 10 yo, large amplitudes and good experimental accuracy are required to detect' these effects. The experiments of Ohmi et al (1976) and Kirmse (1979) do not contain turbulence data. The amplitude of modulation was very small in the experiments of Acharya& Reynolds (1975) andBinder & Kueny (1981).…”

Section: Regime Vmentioning

confidence: 99%

Fully developed periodic turbulent pipe flow. Part 2. The detailed structure of the flow

Ramaprian

1983

J. Fluid Mech.

101

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The main experimental results of the study of periodic turbulent pipe flow have been described in Part 1 of this report. In this second part, these experimental data are examined in greater detail to understand the effect of imposed oscillation on the flow structure, at moderate to large oscillation frequencies. Data on phase and amplitude and energy spectrum are used to study the effect of the imposed oscillation on the turbulence structure at these interactive frequencies of oscillation. Additional experiments which were performed to study the effect of oscillation frequency on the flow structure are also reported. Based on the present observations as well as on the data from other sources, it is inferred that turbulent shear flows respond very differently from laminar shear flows to imposed unsteadiness. A turbulent Stokes number relevant for characterizing the unsteady turbulent shear flows is identified and used to classify such flows.

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Section: Regime Vmentioning

confidence: 99%

Fully developed periodic turbulent pipe flow. Part 2. The detailed structure of the flow

Ramaprian

1983

J. Fluid Mech.

101

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“…By comparison between the results for the various eddy viscosity forms, it was considered that a 4 region variant of the von Karman's [1939] 3 region wall model produced the most reliable analysis of flow behaviour. Ohmi, Usui, Tanaka and Toyama [1976] attempted an experimental verification of the theoretical findings from the previous study. Oscillation frequencies of 0.0432 Hz to 48 Hz were applied to flows with mean Re varying from 7,740 to 95,900.…”

Section: Conclusion For Monotonically Varying Turbulent Pipe Flowmentioning

confidence: 87%

The study of unsteady pipe flow and non-uniform channel flow by the use of laser doppler anemometry

Johnson¹

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Steady fluid flow within circular pipelines has been the subject of very extensive research for well over 100 years. However, unsteady flows, particularly those at transitional and higher Reynolds Numbers, have not been nearly so well analyzed.Consequently, although there is now an essentially complete description of the hydraulic and fluids mechanics aspects of steady flow, the understanding of turbulent unsteady flow phenomena is much less certain.The major difficulty in working in the unsteady flow area is the inherent nature of the flow. That is, the unsteadiness of the velocity vector requires a measurement device that does not rely upon time-averaging techniques to produce estimates of the velocity magnitude. For this reason alone, the laser-Doppler anemometer (LDA) is an ideal instrument for analysis of unsteady flows. In addition, it is non-intrusive and so does not affect the structure of the flow during the measurement process.Experimental procedures were developed successfully to enable the accurate measurement of mean velocity and turbulence intensity in monotonically varying unsteady pipe flow. Previous research at the University of Queensland had produced unexpected results in relation to this class of flow, and it was considered that a more detailed experimental analysis would yield important information.More specifically, the concept of quasi-steadiness of the flow was examined. In parallel with the experimental program, theoretical analyses were undertaken to derive methods for determining whether flow at a particular time instant is quasi-steady in nature. A modified simple power law was developed, which enables the flow rate and velocity profile in a steady turbulent flow to be estimated accurately from a single measurement of the centreline velocity. From the same velocity measurement, a law of the wall was used to derive estimates of the friction velocity and hence turbulence intensities over the entire cross-section. niIt was found that velocity profiles in monotonically unsteady turbulent flow were indistinguishable from the corresponding profiles for steady flow at the equivalent Reynolds Number. However, turbulence intensities, in flow under the effect of an acceleration transient, were shown to be significantly smaller than quasi-steady. This is consistent with a lagging process. Under these conditions, it was also found that the onset of laminar-turbulent transition was very significantly delayed (to Re in excess of 100 X 10^). The behaviour around the time of transition was examined in detail, with the conclusion that transition to fully developed turbulent flow occurred much more rapidly in accelerating flow than under steady flow conditions. The LDA was also used to study the behaviour within an open channel flow transition, where the flow area remains constant throughout the transition, but the aspect ratio varies continuously. The channel chosen was such that the width of flow converged as the bed level fell away. Previous research has shown that this form of channel exhib...

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“…The particular weighting function derived by Zielke has been found to be an accurate description of transient friction both for laminar and low Reynolds number turbulent flows [23]. Vardy and Brown [33,34] and others [46,47] have derived weighting functions appropriate for fully developed turbulent flows. Most proposals share many features, like a pronounced peak or else an integrable singularity as t → 0 and an exponential fall off for large t. We shall take the Vardy and Brown weighting function as paradigmatic [34].…”

Section: Main Approaches To Transient Frictionmentioning

confidence: 99%

Extension of the momentum transfer model to time-dependent pipe turbulence

Calzetta

2012

Phys. Rev. E

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We analyze a possible extension of Gioia and Chakraborty's momentum transfer model of friction in steady turbulent pipe flows (Phys. Rev. Lett. 96, 044502 (2006)) to the case of time and/or space dependent turbulent flows. The end result is an expression for the stress at the wall as the sum of an steady and a dynamic component. The steady part is obtained by using the instantaneous velocity in the expression for the stress at the wall of a stationary flow. The unsteady part is a weighted average over the history of the flow acceleration, with a weighting function similar to that proposed by Brown (Journal of Sound and Vibration 259, 1011 (2003); ibid. 270, 233 (2004)), but naturally including the effect of spatial derivatives of the mean flow, as in the Brunone model (B. Brunone et al., J. of Water Resources Planning and Management 236 (2000)).

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Pressure and Velocity Distributions in Pulsating Turbulent Pipe Flow Part 2 Experimental Investigations

Cited by 12 publications

References 0 publications

Fully developed periodic turbulent pipe flow. Part 2. The detailed structure of the flow

Fully developed periodic turbulent pipe flow. Part 2. The detailed structure of the flow

The study of unsteady pipe flow and non-uniform channel flow by the use of laser doppler anemometry

Extension of the momentum transfer model to time-dependent pipe turbulence

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