CALCULATION OF THE LOCAL RESISTANCE COEFFICIENT OF VISCOUS INCOMBRESSIBLE FLUID FLOW IN A PIPE WITH SUDDEN CONTRACTION

An experimental study was performed to investigate the resistance characteristics of the trilobal throttling element in narrow annular channel, while corresponding flow fields analyzed using Fluent software with RNG k-ε turbulence model based on the structural grid for the trilobal throttling element with different placket angle. A relationship between the packet angle θ and the local resistance coefficient ξ is obtained. Results show that the local resistance coefficient obtained by numerical simulation of the trilobal throttling element in narrow annular channel have a good agreement with the experimental data, and their relative error is less than 8%. This also fully proves that the RNG k-ε turbulence model is suitable for the simulation of the trilobal throttling element in the narrow annular channel. The local resistance coefficient of the trilobal throttling element in narrow annular channel increases with rising packet angle θ, and the relationship is similar to the power function change.

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A Numerical Research of the Resistance Characteristics of the Bottom Nozzle in the Annular Fuel Assembly

Volume 6B: Thermal-Hydraulics and Safety Analyses ◽

10.1115/icone26-82259 ◽

2018 ◽

Author(s):

Duan Minghui ◽

Zhao Minfu

Keyword(s):

Fuel Assembly ◽

Geometric Model ◽

Resistance Coefficient ◽

Local Resistance ◽

Flow Paths ◽

Rod Bundle ◽

Split Ratio ◽

Local Resistance Coefficient ◽

Calculation Results ◽

Numerical Research

The upstream of the bottom nozzle in the annular fuel assembly is the coolant inlet, and the downstream is the fuel rod bundle, which includes both inner and outer coolant flow paths. Therefore, the resistance characteristics of the bottom nozzle are very complex. In order to obtain the nozzle local resistance characteristics, a numerical research has been performed to simulate the bottom nozzle in different flow rates and split ratios with a simplified geometric model by CFX. The calculation results indicated that the local resistance of the bottom nozzle in the annular fuel assembly existed self-modeling phenomenon. The critical Reynolds number wasn’t influenced by the split ratio. The local resistance coefficient of the bottom nozzle was only related to the split ratio. The research has provided an analysis method for the bottom nozzle resistance characteristics research.

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Real Values of Local Resistance Coefficients during Water Flow through Welded Polypropylene T-Junctions

Water ◽

10.3390/w12030895 ◽

2020 ◽

Vol 12 (3) ◽

pp. 895

Author(s):

Marek Kalenik ◽

Marek Chalecki ◽

Piotr Wichowski

Keyword(s):

Water Flow ◽

Resistance Coefficient ◽

Water Supply Systems ◽

Internal Diameter ◽

Local Resistance ◽

Water Flow Velocity ◽

Local Resistance Coefficient ◽

Flow Through ◽

Supply Systems ◽

Resistance Coefficients

The paper presents results of investigation of the local resistance coefficient ζ in welded polypropylene T-junctions with the internal diameter 13.2 mm. The investigations were performed on an independently constructed test rig. The scope of investigations encompassed the T-junctions, which were (1) properly warmed up and properly pressed, (2) poorly warmed up and poorly pressed, or (3) excessively warmed up and excessively pressed. The local resistance coefficients ζ determined by measurements according to the standard PN-EN 1267:2012(Designation of the Polish Standard) were compared to those determined with use of the nomograms recommended for designing water supply systems and installations. Real values of the coefficients ζ, obtained in measurements were significantly higher than those read from the nomograms. The local resistance coefficients ζ in welded polypropylene T-junctions depend on water flow velocity and the manufacturing precision of a T-junction joint.

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Influence Experiment for the Spacing Distance of Orifice Plates to Local Resistance Coefficient in the Pressure Delivery Pipeline

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.744-746.1092 ◽

2015 ◽

Vol 744-746 ◽

pp. 1092-1100 ◽

Cited By ~ 1

Author(s):

Lin Li ◽

Sheng Jin ◽

Zhao Liang Bai

Keyword(s):

Resistance Coefficient ◽

Head Loss ◽

Relative Distance ◽

Local Resistance ◽

Water Losses ◽

Head Losses ◽

Water Head ◽

Local Resistance Coefficient ◽

Local Water ◽

Maximal Relative Error

In order to research the influence rule of the spacing distance between orifice plates to the local resistance coefficient and total local water head losses , carried out the experiment research through set the two different relative distance of orifice plates in the pressure delivery pipeline. The experimental results showed that: When the relative distance, the results of total local water head losses calculated by the traditional hydraulics formula with the real measured data, the maximal relative error was less than 3%. This shown that when the relative distance was big, it was no necessary to consider the influence of the relative distance between orifice plates. However, when the relative distance, the real measured data of the total local water losses was much smaller than the calculated data by the traditional calculation formula, the maximal relative error was reached 239.5%. It was explained that when the relative distance was relative small, existed the adjoining influence between orifice plates, so the total local water losses by the multi-orifice plates was not equal to the sum of each water head loss by the single orifice plate, and the total local head loss was not necessarily increased with the number of orifice plates increasing. Whether or not the increasing total local water head losses was closely related with the relative distance of the orifice plates. The traditional local water head loss calculation formula in the hydraulics should be corrected and modified.

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Experimental Determination of Local Resistance Coefficient of Sudden Expansion Tube

Energy and Power Engineering ◽

10.4236/epe.2015.74015 ◽

2015 ◽

Vol 07 (04) ◽

pp. 154-159 ◽

Cited By ~ 2

Author(s):

Yinpeng Li ◽

Changjin Wang ◽

Mingda Ha

Keyword(s):

Experimental Determination ◽

Resistance Coefficient ◽

Sudden Expansion ◽

Local Resistance ◽

Expansion Tube ◽

Local Resistance Coefficient

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Numerical Calculation of the Tee Local Resistance Coefficient

The Open Mechanical Engineering Journal ◽

10.2174/1874155x01509010876 ◽

2015 ◽

Vol 9 (1) ◽

pp. 876-881 ◽

Cited By ~ 1

Author(s):

Qin Zhang ◽

Manlai Zhang ◽

Zhihong Zhou ◽

Shizhong Wei

Keyword(s):

Cfd Simulation ◽

Flux Ratio ◽

Frictional Resistance ◽

Resistance Coefficient ◽

Head Loss ◽

Local Resistance ◽

Local Resistance Coefficient ◽

Tee Junction ◽

Resistance Coefficients

The local head loss of tee could be calculated with the determination of local resistance coefficient by CFD simulation and test. Based on the mesh-independent feature identified, the flow field inner tee was numerically simulated by the standard k - ε turbulent model and SIMPLEC algorithms, which has revealed the mainstream was obliged to turn to the opposite side of tee junction, and a rise in pressure drop between upstream and downstream was caused as a result. Furthermore, the frictional resistance coefficient was calculated for eliminating the frictional head loss of model, which decreased from 0.0207 to 0.0133 when the inlet velocity increased from 1 m/s to 12 m/s. Additionally, the local resistance coefficients of tee at flow conditions were attained, and the quadratic polynomial between the local resistance coefficient and flux ratio was presented due to the influence of branch on mainstream. Through the test, the simulation result has been compared and the effectiveness of simulation has been verified.

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The Air Consumption Estimation of Convection Heaters with Natural Convection and Water Heat Carrier

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.725-726.1301 ◽

2015 ◽

Vol 725-726 ◽

pp. 1301-1306

Author(s):

Viktor Pukhkal

Keyword(s):

Natural Convection ◽

Heat Flow ◽

Heat Carrier ◽

Natural Circulation ◽

Air Flow ◽

Resistance Coefficient ◽

Local Resistance ◽

Cold Air ◽

Effective System ◽

Local Resistance Coefficient

The knowledge of temperature and air consumption at the output of a convection heater is required to develop an effective system protecting serviced room zones against descending cold air flow near the glassing. The existing method of heat appliances’ study and calculation, which uses an idea of nominal heat flow, does not provide those parameters. The analytic correlation between aerodynamical and thermotechnical characteristics of heat convectors with natural circulation at nominal conditions is established. The experimental estimation of air consumption and local resistance coefficient of „Atoll“ (PKN 309) convection heater is carried out. The obtained dependencies allow calculating temperature and air consumption at convection heater output by the existing method of heat appliances’ calculation using nominal heat flow.

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Plastic Flow in Confined Porous Media of Complex Contours

10.1115/imece1999-1167 ◽

1999 ◽

Author(s):

Mario F. Letelier ◽

César E. Rosas

Keyword(s):

Porous Medium ◽

Porous Media ◽

Fluid Flow ◽

Theoretical Study ◽

Perturbation Parameter ◽

Resistance Coefficient ◽

Boundary Perturbation ◽

Bingham Plastic ◽

Flow Through ◽

Central Plug

Abstract A theoretical study of the fully developed fluid flow through a confined porous medium is presented. The fluid is described by the Bingham plastic model for small values of the yield number. The analysis allows for many admissible shapes of the wall contour. The velocity field is computed for several combination of relevant parameters, i.e., the yield number, Darcy resistance coefficient and the boundary perturbation parameter. The wall effect is especially highlighted and the characteristics of the central plug region as well. Plots of isovel curves and velocity profiles are included for a variety of flow and geometry parameters.

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Numerical Study of Circular Tube inserted Arc Belt on Fluid Flow and Heat Transfer under Laminar Flow

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.561.460 ◽

2013 ◽

Vol 561 ◽

pp. 460-465

Author(s):

Dong Hui Zhang ◽

Jiao Gao

Keyword(s):

Heat Transfer ◽

Fluid Flow ◽

Laminar Flow ◽

Wall Temperature ◽

Circular Tube ◽

Numerical Study ◽

Resistance Coefficient ◽

Uniform Wall Temperature ◽

Flow And Heat Transfer ◽

Uniform Wall

The objective of this paper is to study the characteristic of a circular tube with a built-in arc belt on fluid flow and heat transfer in uniform wall temperature flows. Numerical simulations for hydrodynamically laminar flow was direct ran at Re between 600 and 1800. Preliminary results on velocity and temperature statistics for uniform wall temperature show that, arc belt can swirl the pipe fluid, so that the fluid at the center of the tube and the fluid of the boundary layer of the wall can mix fully, and plays the role of enhanced heat transfer, but also significantly increases the resistance of the fluid and makes the resistance coefficient of the enhanced tube greater than smooth tube. The combination property PEC is all above 1.5.

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