Flow establishment in helical corrugated pipe

1988 ◽  
Vol 15 (5) ◽  
pp. 912-915 ◽  
Author(s):  
Cliff D. Smit
Keyword(s):  
Friction Factor ◽  
Helix Angle ◽  
Head Loss ◽  
Pipe Length ◽  
Head Losses ◽  
A Value ◽  
Variable Friction ◽  
Smooth Pipe ◽  
Loss Term ◽  
Hydraulics Laboratory

Corrugated steel pipe suppliers have recently switched from annular rivetted corrugated pipe to helical lock seam corrugated pipe. This was done as a manufacturing expedient, but there has been an unexpected benefit in terms of reduced hydraulic resistance. Studies on full scale pipes have shown that the friction factor for full flow is lowered substantially as the helix angle of the corrugations is reduced. In fact at a helix angle of 52.5 ° the pipe resistance was found to be almost as low as for smooth pipe. However, these tests were concerned exclusively with determining rates of head loss for fully established flow. Drainage culverts for highways, grid roads, and farm crossings are usually relatively short structures. In some cases the length to diameter ratio may be as low as 10, and in most cases would not exceed 50. This immediately introduces the question of the length of culvert required to develop fully established helical flow, because before the flow becomes established the rate of head loss will be greater. In effect the friction factor will be highest at the culvert inlet and decrease along the length of the culvert, becoming a minimum after the flow is fully established. In theory the accumulated loss could be calculated by using a variable friction factor over the establishment length. This would be cumbersome and impractical. It would be simpler to calculate the pipe friction on the assumption that it is constant, at the minimum value, for the whole length of the pipe and then add a "development head loss" term to account for the extra loss. Experiments to determine the development head loss were conducted at the Hydraulics Laboratory, Department of Civil Engineering, University of Saskatchewan. The model pipes were 107 mm inside diameter and 2.13 m long. Standard corrugations were simulated and helix angles of 61.0 and 71.4° were tested. It was found that about 12 diameters of pipe length were required to obtain fully established flow, and a value for the development head loss of 0.2 times the velocity head was indicated. Key words: helical corrugated pipe, head losses, n values, flow establishment.

scholarly journals Major and minor head losses in a hydraulic flow circuit: experimental measurements and a Moody’s diagram application

2020 ◽  
Vol 45 (3) ◽  
pp. 47-56
Author(s):  
Aline Amaral Madeira
Keyword(s):  
Friction Factor ◽  
Correlation Coefficients ◽  
Head Loss ◽  
Rapid Expansion ◽  
Experimental Measurements ◽  
Hydraulic Systems ◽  
Local Loss ◽  
Hydraulic Flow ◽  
Head Losses ◽  
Flow Circuit

Domestic and industrial hydraulic drainage networks have gradually become more complicated because of the cities’ rapid expansion. In surcharged hydraulic systems, the head losses may become rather significant, and should not be neglected because could result in several problems. This work presents an investigation about major and minor head losses in a hydraulic flow circuit, simulating the water transport in a drainage network at room temperature (298.15 K) under atmospheric pressure (101,325 Pa). The losses produced by the fluid viscous effect through the one used cast-iron rectilinear pipe (RP-11) and the localized losses generated by two flow appurtenances, one fully open ball valve (BV-1) and one module of forty-four 90º elbows (90E-8) were experimentally measured. Experimental data generated head-loss curves and their well fitted to potential regressions, displaying correlation coefficients (R2) of 0.9792, 0.9924, and 0.9820 for BV-1, 90E-8, and RP-11, respectively. Head loss experimental equations and local loss coefficients through BV-1 and 90E-8 were determined successfully. The Moody’s diagram application proved to be a quite appropriate tool for an approximate estimation of Darcy-Weisbach friction factor. A good approximation between friction factor values obtained via experimental measurements and the Moody’s diagram was observed with mean absolute deviate of 0.0136.

scholarly journals Modelling head loss along emitting pipes using dimensional analysis

2015 ◽  
Vol 35 (3) ◽  
pp. 442-457 ◽  
Author(s):  
Acácio Perboni ◽  
Jose A. Frizzone ◽  
Antonio P. de Camargo ◽  
Marinaldo F. Pinto
Keyword(s):  
Dimensional Analysis ◽  
Excellent Result ◽  
Head Loss ◽  
Maximum Deviation ◽  
Maximum Relative Error ◽  
Data Set ◽  
Head Losses ◽  
Model Based ◽  
Precision And Accuracy ◽  
Relative Errors

Local head losses must be considered in estimating properly the maximum length of drip irrigation laterals. The aim of this work was to develop a model based on dimensional analysis for calculating head loss along laterals accounting for in-line drippers. Several measurements were performed with 12 models of emitters to obtain the experimental data required for developing and assessing the model. Based on the Camargo & Sentelhas coefficient, the model presented an excellent result in terms of precision and accuracy on estimating head loss. The deviation between estimated and observed values of head loss increased according to the head loss and the maximum deviation reached 0.17 m. The maximum relative error was 33.75% and only 15% of the data set presented relative errors higher than 20%. Neglecting local head losses incurred a higher than estimated maximum lateral length of 19.48% for pressure-compensating drippers and 16.48% for non pressure-compensating drippers.

scholarly journals PERDA DE CARGA EM TUBULAÇÕES E CONEXÕES CONDUZINDO ÁGUA RESIDUARIA DA AVICULTURA

Irriga ◽  
2007 ◽  
Vol 12 (2) ◽  
pp. 225-234
Author(s):  
Silvio Cesar Sampaio ◽  
Elisandro Pires Frigo ◽  
Marcio Antonio Vilas Boas ◽  
Manoel M. F. de Queiroz ◽  
Benedito Martins Gomes ◽  
...  
Keyword(s):  
Head Loss ◽  
Wastewater Irrigation ◽  
Average Decrease ◽  
Head Losses ◽  
Liquid Behavior ◽  
Connection Type ◽  
Poultry Wastewater ◽  
System Project

PERDA DE CARGA EM TUBULAÇÕES E CONEXÕES CONDUZINDO ÁGUA RESIDUARIA DA AVICULTURA  Silvio Cesar Sampaio; Elisandro Pires Frigo; Marcio Antonio Vilas Boas; Manoel M. F. De Queiroz; Benedito Martins Gomes; Larissa Schmatz MallmannRecursos Hídricos e Saneamento Ambiental, Universidade Estadual do Oeste do Paraná, Cascavel, PR  1 RESUMO O presente trabalho visou estimar a perda de carga em tubulações comerciais utilizando como fluido circulante água residuária de avicultura (ARA). As tubulações utilizadas foram de aço galvanizado e PVC, com diâmetros variando entre32 a75 mm. Construiu-se bancadas de testes para perdas de carga localizada e distribuída. Registrou-se dados de vazão e pressão para os variados tubos e conexões, utilizando os diferentes materiais. Na avaliação dos dados encontrados, os mesmos foram tabelados e ajustados a modelos potenciais para a perda de carga distribuída e fator “k” para perda de carga localizada. Como parâmetro de comparação e avaliação também foram registrados dados utilizando como fluído circulante água de abastecimento urbano (AAU). A ARA apresentou em média uma diminuição de 42 e 21% no valor do coeficiente “C” de rugosidade da equação de Hazen-Williams, quando comparado com a AAU, para os tubos de PVC e aço galvanizado, respectivamente. Para a perda de carga distribuída, estima-se um aumento que varia de31 a8% com a ARA em relação à AAU, porém essa diferença é sujeita a variação da vazão. Nas conexões soldáveis a perda de carga localizada com a ARA foi maior que na AAU, ao contrário das conexões rosqueáveis. UNITERMOS: perda de carga, irrigação, hidráulica.  SAMPAIO, S. C.; FRIGO, E. P.; VILAS BOAS, M. A.; QUEIROZ, M. M. F. de; GOMES, B. M.; MALLMANN, L. S. HEAD LOSSES IN PIPELINES AND CONNECTIONS CARRYING POULTRY WASTEWATER  2 ABSTRACT An appropriate hydraulics system project requires knowledge on liquid behavior in pressurized piping. This work aimed to  evaluate head losses in pipelines and connections carrying poultry wastewater. Commercial  pipelines made of galvanized iron and PVC and diameters from1”to3”were used. Poultry wastewater presented an average decrease of 42 and 21% inHazen-Williams´s coefficient values, when compared to water in PVC and galvanized ion pipelines, respectively. In general, head loss in all pipelines increased from 31 to 8% with poltry wastewater in relation to water. The connection type affected the results in localized head loss with poultry wastewater. KEYWORDS: wastewater, irrigation, hydraulics

Turbulent Flow in the Inlet Region of a Smooth Pipe

1963 ◽  
Vol 85 (1) ◽  
pp. 29-33 ◽  
Author(s):  
A. R. Barbin ◽  
J. B. Jones
Keyword(s):  
Static Pressure ◽  
Turbulence Energy ◽  
Reynolds Stresses ◽  
Calculation Methods ◽  
Mean Velocity ◽  
Pipe Length ◽  
Fully Developed Flow ◽  
Inlet Region ◽  
Smooth Pipe ◽  
Radial Convection

This paper reports measurements of mean velocities, turbulence intensities, and turbulence (Reynolds) stresses in the inlet region of a smooth pipe. Data are presented for the first 40 diameters of pipe length. Fully developed flow is not attained in this length for a Reynolds number (based on pipe diameter and mean velocity) of 388,000, but the wall shear stress and the static pressure gradient attain their fully developed values within the first 15 diameters. Velocity profiles at successive sections in the inlet region are not similar as assumed in some published calculation methods. Longitudinal convection of turbulence energy is appreciable; except very near the pipe entrance, radial convection is negligible.

Turbulent flow in smooth and rough pipes

2007 ◽  
Vol 365 (1852) ◽  
pp. 699-714 ◽  
Author(s):  
J.J Allen ◽  
M.A Shockling ◽  
G.J Kunkel ◽  
A.J Smits
Keyword(s):  
Reynolds Number ◽  
Friction Factor ◽  
Outer Layer ◽  
Strong Support ◽  
Reynolds Numbers ◽  
Mean Velocity ◽  
Number Range ◽  
Princeton University ◽  
Smooth Pipe ◽  
Logarithmic Region

Recent experiments at Princeton University have revealed aspects of smooth pipe flow behaviour that suggest a more complex scaling than previously noted. In particular, the pressure gradient results yield a new friction factor relationship for smooth pipes, and the velocity profiles indicate the presence of a power-law region near the wall and, for Reynolds numbers greater than about 400×10 3 ( R + >9×10 3 ), a logarithmic region further out. New experiments on a rough pipe with a honed surface finish with k rms / D =19.4×10 −6 , over a Reynolds number range of 57×10 3 –21×10 6 , show that in the transitionally rough regime this surface follows an inflectional friction factor relationship rather than the monotonic relationship given in the Moody diagram. Outer-layer scaling of the mean velocity data and streamwise turbulence intensities for the rough pipe show excellent collapse and provide strong support for Townsend's outer-layer similarity hypothesis for rough-walled flows. The streamwise rough-wall spectra also agree well with the corresponding smooth-wall data. The pipe exhibited smooth behaviour for , which supports the suggestion that the original smooth pipe was indeed hydraulically smooth for Re D ≤24×10 6 . The relationship between the velocity shift, Δ U / u τ , and the roughness Reynolds number, , has been used to generalize the form of the transition from smooth to fully rough flow for an arbitrary relative roughness k rms / D . These predictions apply for honed pipes when the separation of pipe diameter to roughness height is large, and they differ significantly from the traditional Moody curves.

Head losses at manholes with a 90° bend

1988 ◽  
Vol 15 (5) ◽  
pp. 851-858 ◽  
Author(s):  
J. Marsalek ◽  
B. J. Greck
Keyword(s):  
Key Words ◽  
Channel Flow ◽  
Open Channel ◽  
Open Channel Flow ◽  
Head Loss ◽  
Pipe Diameter ◽  
Head Losses ◽  
Junction Geometry ◽  
Pressure Changes

Head and pressure changes were studied at manholes with a 90° bend. For pressurized flow, such changes depend only on junction geometry. Among junction parameters, the benching was found particularly important. Full benchings reaching to the pipe crown produced the lowest head losses, particularly when combined with an enlarged pipe diameter at the junction. Head changes in open-channel flow were significantly smaller than those in pressurized flow. Key words: head loss, manholes, sewer junctions, sewer design, sewer hydraulics.

scholarly journals PERDA DE CARGA EM FITAS GOTEJADORAS COM EMISSORES MOLDADOS

Irriga ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 86-93
Author(s):  
Verônica Gaspar Martins Leite de Melo ◽  
Leonardo Leite de Melo ◽  
José Antônio Frizzone ◽  
Antônio Pires de Camargo ◽  
Patricia Angélica Alves Marques
Keyword(s):  
Friction Factor ◽  
Drip Irrigation ◽  
Irrigation System ◽  
Low Cost ◽  
Pressure Head ◽  
Head Loss ◽  
Operating Pressure ◽  
Relative Errors ◽  
E Mail ◽  
Pipe Inlet

PERDA DE CARGA EM FITAS GOTEJADORAS COM EMISSORES MOLDADOS     VERÔNICA GASPAR MARTINS LEITE DE MELO1; LEONARDO LEITE DE MELO2; JOSÉ ANTÔNIO FRIZZONE3; antônio pires de camargo4 E patricia algélica alves marques5   1 Departamento de Engenharia de Sistemas Agrícola, ESALQ/USP, Av. Pádias, 11, São Dimas, CEP13418-900, Piracicaba, SP, Brasil, e-mail: [email protected] 2 Departamento de Engenharia de Sistemas Agrícola, ESALQ/USP, Av. Pádias, 11, São Dimas, CEP13418-900, Piracicaba, SP, Brasil, e-mail: [email protected] 3 Departamento de Engenharia de Sistemas Agrícola, ESALQ/USP, Av. Pádias, 11, São Dimas, CEP13418-900, Piracicaba, SP, Brasil, e-mail: [email protected] 4 Faculdade de Engenharia Agrícola – UNICAMP, Av. Cândido Rondon, 501, Cidade Universitária, CEP 13083 - 875, Campinas, SP, e-mail: [email protected] 5 Departamento de Engenharia de Sistemas Agrícola, ESALQ/USP, Av. Pádias, 11, São Dimas, CEP13418-900, Piracicaba, SP, Brasil, e-mail: [email protected]     1 RESUMO   Embora as fitas gotejadoras sejam de baixo custo, é importante que esse material seja avaliado hidraulicamente para prover informações técnicas. O objetivo deste trabalho foi analisar a perda contínua de carga e o fator de atrito em uma fita gotejadora com emissor moldado em seu interior. O experimento foi conduzido no laboratório de irrigação da ESALQ/USP. Utilizou-se a fita gotejadora Rain-Tape® fabricada pela Rain Bird®, espessura de parede de 225 µm e emissores tipo labirinto, espaçados de 0,30 m, vazão nominal de 1 L h-1 e pressão de serviço de 55 kPa. A equação de perda de carga para regime de escoamento turbulento liso em função da vazão e da carga de pressão na entrada da fita apresenta boa habilidade para estimar a perda de carga em fitas gotejadoras com emissores moldados, sendo que 95% das estimativas apresentaram erro relativo de até 6,71%. A equação de Darcy-Weisbach pode ser utilizada para o cálculo da perda de carga desde que o diâmetro seja substituído por uma função da pressão de entrada. Para o cálculo da perda de carga, utilizando a equação de Darcy-Weisbach, o fator de atrito calculado pela equação de Blasius deve considerar um coeficiente a = 0,3408.   Palavras-chave: irrigação por gotejamento, perda de carga por atrito, fator de atrito     MELO, V. G. M. L. de; MELO, L. M. de; FRIZZONE, J. A.; CAMARGO, A. P. de; MARQUES, P. A. A. HEAD LOSS IN DRIP TAPES WITH MOLDED EMITTERS     2 ABSTRACT   Although drip tapes are low-cost equipment, proper hydraulic evaluation is important to provide information required for irrigation system design. The aim of this study was to analyze the friction head loss and the friction factor in drip tapes with molded emitters, that are employed in drip irrigation systems. Experiments evaluated the drip tape model Rain-Tape®, manufactured by Rain Bird, 225-µm wall thickness, labyrinth-type emitters, 0.30-m emitters spacing, 1 L h-1 nominal discharge and operating pressure of 55 kPa. The following conclusions were obtained: (a) the equation of head loss for smooth turbulent flow as a function of flow rate and pressure head at the pipe inlet provided good predictions of head loss in drip tapes with molded emitters, since 95% of predictions presented relative errors less than 6.71%; (b) the Darcy-Weisbach equation may be used for calculating head loss, but the pipe diameter must be replaced by a function considering the lateral inlet pressure; (c) for calculating head loss of the Rain-Tape using the Darcy-Weisbach equation, the friction factor obtained by the Blasius equation should use the coefficient a = 0.3408.   Keywords: drip irrigation, frictional head loss, friction coefficient

scholarly journals Scaling of permeabilities and friction factors of homogeneously expanding gas-solids fluidized beds: Geldart’s A powders and magnetically stabilized beds

2006 ◽  
Vol 10 (1) ◽  
pp. 19-44 ◽  
Author(s):  
Jordan Hristov
Keyword(s):  
Pressure Drop ◽  
Friction Factor ◽  
Channel Model ◽  
Fluid Velocity ◽  
Scaling Law ◽  
Special Problem ◽  
Transfer Coefficients ◽  
Forchheimer Equation ◽  
Minimization Method ◽  
Variable Friction

The concept of a variable friction factor of fluid-driven de form able powder beds undergoing fluidization is discussed. The special problem discussed addresses the friction factor and bed permeability relationships of Geldart?s A powders and magnetically stabilized beds in axial fields. Governing equations and scaling relation ships are developed through three approaches (1) Minimization of the pressure drop with respect to the fluid velocity employing the Darcy-Forchheimer equation together with the Richardson-Zaki scaling law, (2) Minimization of the pres sure drop across an equivalent-channel replacing the actual packed beds by a straight pipe with bed-equivalent obstacle of a simple geometry, and (3) Entropy minimization method applied in cases of the Darcy-Forchheimer equation and the equivalent-channel model. Bed-to-surface heat transfer coefficients are commented in the context of the porosity/length scale relationships developed. Both the pressure drop curves developments and phase diagram de signs are illustrated by applications of the intersection of asymptotes technique to beds exhibiting certain degree of cohesion.

scholarly journals Local head loss caused in connections used in micro-irrigation systems

2019 ◽  
Vol 23 (7) ◽  
pp. 492-498 ◽  
Author(s):  
Wagner W. Á. Bombardelli ◽  
Antonio P. de Camargo ◽  
José A. Frizzone ◽  
Rogério Lavanholi ◽  
Hermes S. da Rocha
Keyword(s):  
Flow Rate ◽  
Head Loss ◽  
International Standards ◽  
Flow Conditions ◽  
Irrigation Systems ◽  
Head Losses ◽  
Satisfactory Performance ◽  
Head Loss Coefficient ◽  
Micro Irrigation ◽  
The One

ABSTRACT Information about local head loss caused by connections employed in micro-irrigation systems is hard to be found in literature. The objective of this research was to experimentally determine the local head losses in connections commonly used in micro-irrigation and propose mathematical models using the theorem of Buckingham. The methodology of tests was based on international standards. The tests were carried out under controlled inlet pressure, at 150 kPa, and five to ten units of each connection model were tested. The curves relating flow and head losses were drawn based on 15 flow conditions, obtained under increase and decrease of flow rate. For each condition, 30 points were collected resulting in a sample size of 900 points in each test. For each connection model evaluated, the following information was obtained: curves of local head loss as a function of flow rate and of local head loss coefficient (KL). The obtained values of KL ranged from 2.72 to 24.16, which become constant for Reynolds number higher than 10,000. The sensitivity of the coefficient related to a ratio of the internal sections in the connections was also verified. The flow exponents presented values close to the one applied by the Darcy-Weisbach equation (m = 2). The models developed for the connections presented a satisfactory performance.

Turbulent Flow in Closely-Pitched Internally Enhanced Tubes

2000 ◽  
Author(s):  
T. S. Ravigururajan ◽  
J. Srinivasan
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Friction Factor ◽  
Helix Angle ◽  
Independent Study ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Flow Parameters ◽  
Wide Range ◽  
Enhanced Tubes

Abstract General correlations are developed and verified for friction factor and heat transfer coefficients for single-phase turbulent flow in internally augmented tubes, with low pitch to height ratios. Data from existing investigations were collected for a wide range of tube parameters with e/d: 0.01 to 0.2; p/e: < 8; α/90: 0.2 to 1.0, and flow parameters; Re: 2000 to 250,000 and Pr: 0.66 to 37.6. The data were applied to a linear model to get normalized correlations that were then modified to approach smooth tube correlations, as the roughness variables became very small. The correlations predicted 92% of data from an independent study on microfin tubes within ± 30%. For closely-pitched enhanced tubes, the proposed correlations predict heat transfer/friction factor with better overall accuracy and are suitable for different types of internal enhancements. The heat transfer increases with decreasing p/e ratio and increasing helix angle. The effects of roughness height and pitch on both friction and heat transfer are similar to that experienced in traditional enhancement design (p/e > 8).

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