Comparison of approximate and exact description of isoviscous flow velocity profile formed in rectangular cross-section channel for field-flow fractionation

The results of experimental and computational studies of the three-dimensional mean flow velocity profile influence on the impedance eduction are presented. In order to measure the three-dimensional velocity profile, the TsAGIâ€(tm)s â€œInterferometer with flowâ€ facility was upgraded so that additional holes were made in one cross section of the rectangular duct. As a result, it became possible to measure the longitudinal flow velocity in this cross section along 6 lines using a Pitot tube or a hot wire anemometer. The full three-dimensional velocity profile is determined by interpolating the values measured.Experimental results of the velocity profile for various experiment conditions are presented. Based on the numerical solution of the three-dimensional Pridmore-Brown equation by means of Finite Element Method and the gradient descent method, the problem of impedance eduction are investigated. The influence of the flow velocity profile and the form of functional on the obtained impedance values are discussed. The impedance values educted by means of this approach are compared with the impedance values obtained using two-dimensional impedance eduction methods, which didnâ€(tm)t taking into account the three-dimensional non homogeneity of the flow velocity field.

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Visualization and measurement of flow velocity profile in a U-bend of square cross-section using a laser induced fluorescence method.

JOURNAL OF THE FLOW VISUALIZATION SOCIETY OF JAPAN ◽

10.3154/jvs1981.6.377 ◽

1986 ◽

Vol 6 (22) ◽

pp. 377-382 ◽

Cited By ~ 2

Author(s):

Kenkichi OHBA ◽

Makoto SATO

Keyword(s):

Velocity Profile ◽

Flow Velocity ◽

Cross Section ◽

Laser Induced Fluorescence ◽

Fluorescence Method ◽

Flow Velocity Profile

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Investigation of ultrasonic flowmeter error in distorted flow using two-peak Salami functions

Energy Engineering and Control Systems ◽

10.23939/jeecs2021.02.144 ◽

2021 ◽

Vol 7 (2) ◽

pp. 144-151

Author(s):

Fedir Matiko ◽

◽

Vitalii Roman ◽

Halyna Matiko ◽

Dmytro Yalinskyi

Keyword(s):

Velocity Profile ◽

Flow Velocity ◽

Cross Section ◽

Ultrasonic Flowmeter ◽

Additional Error ◽

Average Flow ◽

Research Results ◽

Pipe Cross Section ◽

Average Flow Velocity ◽

Flow Velocity Profile

Results of investigating the additional error of ultrasonic flowmeters caused by the distortion of the flow are presented in the article. The location coordinates of acoustic paths were calculated for their number from 1 to 6 according to the different numerical integrating methods: Gauss (Gauss-Legendre, Gauss-Jacobi), Chebyshev (equidistant location of acoustic paths), Westinghouse method, method of OWICS (Optimal Weighted Integration for Circular Sections). This made it possible to realize the flowrate equation for multi-path ultrasonic flowmeters and to determine their additional error for different location of the acoustic paths. The average flow velocity along each path is calculated based on the flow velocity profile in the pipe cross section. Four two-peak Salami functions of velocity are used to calculate the velocity profile of the distorted flow caused by typical local resistances. According to the research results the recommendations were developed for choosing the number of the acoustic paths of the ultrasonic flowmeters and for using the methods for determining the location coordinates of the acoustic paths.

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Investigation of the influence of the flow structure on the accuracy of flow measurement before a hydrometric structure in an open channel

Melioration and Water Management ◽

10.32962/0235-2524-2019-5-41-44 ◽

2020 ◽

pp. 41-44

Author(s):

Anatoly Kusher

Keyword(s):

Velocity Profile ◽

Flow Velocity ◽

Water Flow ◽

Flow Measurement ◽

Water Discharge ◽

Critical Depth ◽

Flow Measurements ◽

Study Results ◽

Flow Velocity Profile ◽

Upstream Flow

The reliability of water flow measurement in irrigational canals depends on the measurement method and design features of the flow-measuring structure and the upstream flow velocity profile. The flow velocity profile is a function of the channel geometry and wall roughness. The article presents the study results of the influence of the upstream flow velocity profile on the discharge measurement accuracy. For this, the physical and numerical modeling of two structures was carried out: a critical depth flume and a hydrometric overfall in a rectangular channel. According to the data of numerical simulation of the critical depth flume with a uniform and parabolic (1/7) velocity profile in the upstream channel, the values of water discharge differ very little from the experimental values in the laboratory model with a similar geometry (δ < 2 %). In contrast to the critical depth flume, a change in the velocity profile only due to an increase in the height of the bottom roughness by 3 mm causes a decrease of the overfall discharge coefficient by 4…5 %. According to the results of the numerical and physical modeling, it was found that an increase of backwater by hydrometric structure reduces the influence of the upstream flow velocity profile and increases the reliability of water flow measurements.

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