Refinement of turbulent flow velocity characteristics

Bryanskaya, Yuliya

doi:10.5862/mce.41.4

Cited by 4 publications

(3 citation statements)

References 4 publications

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“…Comparison of the formulas (15) and (16) showed that the Laplace formula corresponds quite accurately to the dependence (16) Using the dependence (17), it is true for wave perturbations having a length commensurate with the depth of the flow, the condition V k =С gives: The calculations according to (18) show that the critical Froude number is significantly less than 1 under wave disturbances, the length of which is less than 2πh.…”

Section: Methods and Resultsmentioning

confidence: 93%

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The conditions for occurrence of critical flow regime of water in the open stream

Bryanskaya

Ostiakova

2019

E3S Web Conf.

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For the solution of engineering problems require increasingly accurate estimates of the hydraulic characteristics of the water streams. To date, it is impossible to consider sufficiently complete theoretical and experimental justification of the main provisions of the theory of turbulence, hydraulic resistance, channel processes. The composition of tasks related to flows in wide channels, turbulence problems are of scientific and practical interest. Various interpretations of the determination of the critical Froude number in wide open water flows based on observations and theoretical transformations are considered. The conditions for the emergence of a critical regime of water flow in an open wide channel are analyzed in order to estimate the critical Froude number and critical depth. Estimates of the critical Froude number for laboratory and field conditions are given. The estimations allow us to consider the proposed approach acceptable for determining the conditions of occurrence of the critical flow regime. The General, physical interpretation of conditions of occurrence of the critical regime of water flow on the basis of phenomenological approach is specified. The results take into account the values of the components of the total specific energy of the section. This shows the estimated calculation. The results obtained theoretically make it possible to compare the above interpretations and determine their applicability, and the results of the analysis can be useful for the estimated calculations of flows in channels and river flows in rigid, undeformable boundaries and with minor channel deformations.

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Section: Methods and Resultsmentioning

confidence: 93%

“…1). With this deviation, the depth of the flow changes towards a smaller or larger value of the conjugate depths corresponding to the specific energy of the cross section after the change [2,5,8,[15][16][17][18][19][20]. In this case, the water surface is either a bumpy, unstable, wave surface, or there is a hydraulic jump.…”

Section: Methods and Resultsmentioning

confidence: 99%

The conditions for occurrence of critical flow regime of water in the open stream

Bryanskaya

Ostiakova

2019

E3S Web Conf.

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“…The purpose of the experiments was to provide special conditions for the liquid flow with a forced agitation of suspended substances in it by creating various structured relief surfaces on the tray inner surface. Herewith, a prospective model of the particle motion was considered not as their spontaneous drawing in the bottom part of the pipe, but as a spasmodic movement in the flow (without caking) [18]. In this case, the amount of the deposed sediments remains minimal regardless of the rates and the fillings of the pipeline.…”

Section: Methodsmentioning

confidence: 99%

Experimental studies of the transporting capacity of the pipe textured relief trays

Orlov

Dezhina

2018

MATEC Web Conf.

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The article presents an analysis of theoretical approaches to assessing the gravity pipeline efficiency in the transportation of water containing suspended solids (the sand). The attention is focused on application of the pipeline protective coatings used in their trenchless repair. Provision has been made of studying the problems of the removal of caked deposits on the pipe walls by creating a special pipeline textured inner surface, representing some kind of a relief, which favors the forced effect of flow turbulence in combination with the hydrophobic properties of the pipeline inner surface. The article presents the results of the research works on the creation of small-size hydraulic benches, which allow determination of the degree of the flow hydrophobicity and the transporting capacity along various textured surfaces (the pipeline protective coatings). The article describes the methods of work on the benches, types of obstacles and the nature of their arrangement along the length of the tray. Provision has been made of different options of the pipeline surface relief further improvement. The photo and film fixation, as well as the black-and-white shadow effects, have enabled presentation of the results of full-scale research experiments on the removal of various size suspended solids from the pipeline tray part. The micro-turbulence phenomena depending on the height of obstacles and their location have been described. The prospects and practical significance of the works aimed at improving the flow transport capacity have been assumed.

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Velocity Distribution in Rough Pipe: the Model Based on the Analytical Description of Resistance Curves in Nikuradse’s Experiments

Dudar

2019

IOP Conf. Ser.: Mater. Sci. Eng.

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Calculation and optimization of such complex systems as ventilating networks, water supply systems, etc. taking into account roughness of a surface and possible processes of heat and mass transfer demands use simple hydrodynamic models, which are at the same time sufficiently exact for engineering calculations. The goal of this paper is to develop such model. Prandtl’s model of a two-layer flow in the smooth pipe with the linear law of velocity distribution for a near-wall laminar layer and the logarithmic law for a turbulent core is used as a basis, which spreads to a case of rough pipes. The velocity profile equation and also the equations for the coordinate Yb of the laminar and turbulent border and its velocity Ub are derived. This paper is based on the use of the analytical description of Nikuradse’s experimental curves λ(Re,δ) (λ is the resistance coefficient, δ is the relative roughness) which earlier was found by the author. The dependence λ(Re*,δ) (Re* is the dynamic Reynolds number) is included into all above-mentioned equations. Results of numerical calculations of Yb and Ub as functions of Re* for the values of δ which are the same as in Nikuradse’s experiments are given. The calculation of velocity profiles for some values of Re* and δ is also fulfilled. Comparisons with the experimental velocity profiles obtained by Nikuradse demonstrate a good agreement.

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Refinement of turbulent flow velocity characteristics

Cited by 4 publications

References 4 publications

The conditions for occurrence of critical flow regime of water in the open stream

The conditions for occurrence of critical flow regime of water in the open stream

Experimental studies of the transporting capacity of the pipe textured relief trays

Velocity Distribution in Rough Pipe: the Model Based on the Analytical Description of Resistance Curves in Nikuradse’s Experiments

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