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.

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 New explicit correlation to compute the friction factor under turbulent flow in pipes

2021 ◽  
Vol 25 (7) ◽  
pp. 439-445
Author(s):  
Alan Olivares Gallardo ◽  
Rodrigo Guerra Rojas ◽  
Marco Alfaro Guerra
Keyword(s):  
Turbulent Flow ◽  
Friction Factor ◽  
Hydraulic Systems ◽  
Head Losses ◽  
Explicit Correlation

HIGHLIGHTS The correlation facilitates the calculation of head losses in hydraulic systems. The correlation was design for regimes of high and low turbulence. The best performance of the correlation is obtained for a range of roughness that goes from 10-2 to 5 × 10-3.

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

scholarly journals Verification of CFD tool for simulation of cavitating flows in hydraulic systems

2017 ◽  
Vol 19 (5) ◽  
pp. 653-665 ◽  
Author(s):  
Agnieszka Niedźwiedzka ◽  
Seweryn Lipiński ◽  
Sebastian Kornet
Keyword(s):  
Statistical Analysis ◽  
Volume Fraction ◽  
Correlation Coefficients ◽  
Hydraulic Systems ◽  
Computer Methods ◽  
Main Challenge ◽  
Cavitation Intensity ◽  
History Of ◽  
Fluent Software ◽  
Verification Process

Cavitation is an undesirable phenomenon in hydraulic systems, as it causes erosion and noise. The main difficulty in cavitation prediction when using Fluent software is lack of an openly accessible tool for implementation of a freely chosen homogeneous cavitation model. In this paper the main challenge is to make such a tool, user defined function (UDF). The second challenge is to use a qualitative method in the assessment of the results of verification process. Three cavitation models are verified in Fluent 14.5: Singhal et al., Schnerr & Sauer and Zwart et al. The verification is based on the benchmark example from the Cavitation Modeling tutorial. Three methods of the algorithms verification are used: analysis of the convergence history of volume fraction, comparison of vapour volume fractions and statistical analysis of these data. The original achievements are not only the verified codes but also statistical analysis based on the computer methods of image analysis performed using two correlation coefficients: the first based on the cavitation intensity, and the second based on the changes of the cloud shape. The results of the analyses do not give any reasons to reject the UDFs. The appendix contains the analysed codes (available with the online version of this paper).

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 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.

Experimental and Numerical Analyses of Friction Factors in Offset Strip Fin Heat Exchangers

2007 ◽  
Author(s):  
Aihua Wang ◽  
Samir F. Moujaes ◽  
Yitung Chen ◽  
Valery Ponyavin
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Heat Exchanger ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Experimental Measurements ◽  
Test Rig ◽  
Compact Heat Exchangers ◽  
Friction Factors ◽  
Offset Strip Fin

Heat transfer in compact heat exchangers is augmented by the introduction of the offset strip fins. With the breakdown of the thermal and hydro boundary layers to boost heat transfer, the fins increase the friction power. Two heat exchangers of different fin geometries structures were built and tested. The results of the study show that the round-edge-fin heat exchanger has the smaller friction factor. A test rig was constructed to measure the friction factor of the offset strip fin heat exchangers with air. A modified hydraulic diameter was used to calculate the main parameters. The computational fluid dynamics package FLUENT was used to predict the flow in the heat exchanger. The numerical investigation was conducted and compared with experimental measurements.

scholarly journals Estimation of Cavitation Limits From Local Head Loss Coefficient

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Raúl Sánchez ◽  
Luis Juana ◽  
Francisco V. Laguna ◽  
Leonor Rodríguez-Sinobas
Keyword(s):  
Boundary Conditions ◽  
Distribution Systems ◽  
Water Distribution ◽  
Head Loss ◽  
Cavitation Number ◽  
Distribution Analysis ◽  
Simple Formulation ◽  
Vapor Cavity ◽  
Head Losses ◽  
Minimum Value

Cavitation effects in valves and other sudden transitions in water distribution systems are studied as their better understanding and quantification is needed for design and analysis purposes and for predicting and controlling their operation. Two dimensionless coefficients are used to characterize and verify local effects under cavitating flow conditions: the coefficient of local head losses and the minimum value of the cavitation number. In principle, both coefficients must be determined experimentally, but a semianalytical relationship between them is here proposed so that if one of them is known, its value can be used to estimate the corresponding value of the other one. This relationship is experimentally contrasted by measuring head losses and flow rates. It is also shown that cavitation number values, called cavitation limits, such as the critical cavitation limit, can be related in a simple but practical way with the mentioned minimum cavitation number and with a given pressure fluctuation level. Head losses under conditions of cavitation in sharp-edged orifices and valves are predicted for changes in upstream and downstream boundary conditions. An experimental determination of the coefficient of local head losses and the minimum value of the cavitation number is not dependent on the boundary conditions even if vapor cavity extends far enough to reach a downstream pressure tap. Also, the effects of cavitation and displacement of moving parts of valves on head losses can be split. A relatively simple formulation for local head losses including cavitation influence is presented. It can be incorporated to water distribution analysis models to improve their results when cavitation occurs. Likewise, it can also be used to elaborate information about validity limits of head losses in valves and other sudden transitions and to interpret the results of head loss tests.

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