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.

scholarly journals Head loss in laser-perforated thin-walled polyethylene pipes for irrigation

2019 ◽  
Vol 23 (5) ◽  
pp. 317-323 ◽  
Author(s):  
Verônica G. M. L. de Melo ◽  
José A. Frizzone ◽  
Antonio P. de Camargo ◽  
Wagner W. Á. Bombardelli
Keyword(s):  
Flow Rate ◽  
Pressure Head ◽  
Head Loss ◽  
Internal Diameter ◽  
Thin Wall ◽  
Operating Pressure ◽  
Irrigation Systems ◽  
Polyethylene Pipes ◽  
Flexible Pipes ◽  
Thin Walled

ABSTRACT For reducing fixed and operational costs in pressurized irrigation systems, thin-walled polyethylene pipes with laser-perforated orifices are manufactured to operate under low pressure (up to 100 kPa). Hydraulic characterization of these materials is essential for designing irrigation systems. Considering the material elasticity and the thin wall thickness (about 200 μm), the internal diameter of these pipes may vary according to the operating pressure, resulting in changes of head losses. The purpose of this study was to analyze the head loss in flexible pipes with laser-perforated orifices, and to estimate the maximum length of laterals based on criteria of water distribution uniformity. Non-perforated pipe samples were tested to obtain equations of friction loss. Equations were fitted as a function of flow rate and pressure head at the pipe inlet, and, alternatively, the Darcy-Weisbach equation was modified considering the diameter expressed as a power-law function of pressure head. The equation of head loss as a function of flow rate and pressure head provided proper estimations and considered effects related to changes in the diameter of plastic pipes due to variations in the pressure head. The Darcy-Weisbach equation can be employed for estimating head loss in flexible pipes, whose diameter varies due to pressure, but the diameter must be calculated as a function of the pressure head at the lateral inlet.

scholarly journals Physical Simulation for the Flow in Straight and Rectangular Loop Manifolds

2021 ◽  
Vol 27 (3) ◽  
pp. 15-32
Author(s):  
Abdullah A. Rihan ◽  
Thamer A. Mohamed ◽  
Dr. Wissam H. Alawee
Keyword(s):  
Physical Simulation ◽  
Flow Distribution ◽  
Head Loss ◽  
Flow Conditions ◽  
Factors Affecting ◽  
Uniformity Coefficient ◽  
Head Losses ◽  
Supply Tank ◽  
Total Head ◽  
Constant Head

The flow in a manifolds considered as an advanced problem in hydraulic engineering applications. The objectives of this study are to determine; the uniformity qn/q1 (ratio of the discharge at last outlet, qn to the discharge at first outlet, q1) and total head losses of the flow along straight and rectangular loop manifolds with different flow conditions. The straight pipes were with 18 m and 19 m long and with of 25.4 mm (1.0 in) in diameter each. While, the rectangular close loop configuration was with length of 19 m and with diameter of 25.4 mm (1.0 in) also. Constant head in the supply tank was used and the head is 2.10 m. It is found that outlets spacing and manifold configuration are the main factors affecting the uniformity of flow distribution and friction head losses along manifolds. For large value of outlets spacing, the uniformity coefficient (qn/q1) was found with greatest value of 0.96. Thus, the flow distribution improves with bigger spacing between outlets along manifold. For same manifold length, diameter, inlet head and spacing between outlets (S/L=0.079), the uniformity coefficient was found 0.881 or 88.1% for straight manifold and 0.926 for rectangular loop manifold. From the experimental data, a better uniformity is obtained from the rectangular loop manifold, this is because the friction head loss in rectangular loop manifold was lower than that in straight manifold. The lowest of total head losses was found with greatest outlet spacing along manifold, while the highest of total head losses was found with smallest outlets spacing along manifold. And, the lowest of total head loss was found with the rectangular manifold, while the highest of total head loss was found with the straight manifold.

A Unifying Method for Sizing Throttling Valves Under Laminar or Transitional Flow Conditions

1993 ◽  
Vol 115 (1) ◽  
pp. 166-169
Author(s):  
H. D. Baumann
Keyword(s):  
Experimental Data ◽  
Reynolds Number ◽  
Laminar Flow ◽  
Prediction Method ◽  
Head Loss ◽  
Transitional Flow ◽  
Velocity Head ◽  
Reasonable Accuracy ◽  
Flow Conditions ◽  
Head Loss Coefficient

The mass flow passing through a given valve will decrease in Reynolds number ranges below approximately 10,000 due to the transition from fully developed turbulent to laminar flow. The objective of this study is to provide a uniform prediction method to establish, with reasonable accuracy, the ratio between the turbulent and transitional or laminar flow rate passing through a given valve, taking into account the valve’s hydraulic diameter and the initial turbulent velocity head loss coefficient. Experimental data from prior research tends to support a proposed “unified sizing method” that is applicable for all single-stage valves regardless of size or type.

scholarly journals Effect of the Concentration of Sand in a Mixture of Water and Sand Flowing through PP and PVC Elbows on the Minor Head Loss Coefficient

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 828 ◽  
Author(s):  
Wichowski ◽  
Siwiec ◽  
Kalenik
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Cross Validation ◽  
Head Loss ◽  
Loss Coefficient ◽  
Number Range ◽  
Head Losses ◽  
Grain Sizes ◽  
Head Loss Coefficient ◽  
The Mathematical Model

The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g·L−1, 10.84 g·L−1, and 15.73 g·L−1. The tests were carried out at variable flow velocities for three elbow diameters of 63 mm, 75 mm, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L−1, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6 × 104–2.1 × 105, by 0.3–0.01% for PP63, 0.6–0.03% for PP75, 1.1–0.06% for PP90, 0.8−0.01% for PVC63, 0.8–0.02% for PVC75, and 0.9–0.04% for PVC90. An increase in Re from 5 × 104 to 2 × 106 for elbows with diameters of 63, 75 and 90 mm caused a 7.3%, 6.8%, and 6.0% decrease in the minor head loss coefficient, respectively.

scholarly journals Design and Testing of a Low-Cost and Low-Maintenance Drip Irrigation Filtration System for Micro-Irrigation in Developing Countries

2014 ◽  
Author(s):  
Alison Greenlee ◽  
Timothy Murray ◽  
Victor Lesniewski ◽  
Mark Jeunnette ◽  
Amos G. Winter
Keyword(s):  
Flow Rate ◽  
Drip Irrigation ◽  
Pressure Loss ◽  
Low Cost ◽  
Irrigation Systems ◽  
Pressure Losses ◽  
Filtration System ◽  
Cartridge Filter ◽  
Micro Irrigation ◽  
Design And Testing

The cylindrical filters presently used in <1000 m2 drip irrigation systems are frequently clogged, increasing pressure loss and lowering the flow rate through the filters. This work investigates the mechanisms for this clogging and proposes an alternative filtration design that would enable both more reliable and lower maintenance filtering. This proposed system is compatible with existing drip irrigation systems and could be made inexpensively with plastic bottle manufacturing equipment. To compare the proposed design to off-the-shelf options, a drip irrigation test setup was built to measure the pressure loss across different filters as particles accumulated. These experiments confirmed that pleated cartridge filters, with high effective surface area, incurred lower pressure losses than cylindrical filters. These tests revealed that the greatest reason for clogged performance was that filtered particles (not the cartridge filter itself) eventually restricted the flow of water through the system. This inspired the redesign of the filter housing such that the housing extended far below the filter, providing a catch basin away from the filter for the particles to settle. Fixing the filter independently of the bottom casing significantly improved the overall performance of the filtration system, reduced the maintenance requirement necessary from the user, and would enable inexpensive manufacturing via blow molding. This paper experimentally demonstrates that the cartridge filter inside the redesigned housing can filter out over 2 kg of sand while maintaining less than a .03 bar pressure drop across the filter at a flow rate of 25 l/s.

scholarly journals Development and Evaluation of Low Cost Drip Filter

2020 ◽  
pp. 87-94
Author(s):  
Balaji Kannan ◽  
N. Janani ◽  
S. Thangamani ◽  
A. Selvaperumal
Keyword(s):  
Pressure Drop ◽  
Flow Rate ◽  
Irrigation System ◽  
Low Cost ◽  
Water Productivity ◽  
Head Loss ◽  
Single Chamber ◽  
Uniformity Coefficient ◽  
Sand Particles ◽  
Micro Irrigation

Irrigation water is many a time contaminated with physical, chemical and biological impurities. Proper filtration is of paramount importance to prevent clogging in drip irrigation system thereby aiding in reduced maintenance of the micro irrigation system. This study was conducted on Development and Evaluation of Low cost filters in the Network project on “Engineering Interventions in Micro Irrigation Systems (MIS) for improving water productivity” under Consortia Research Platform on Farm Mechanization and Precision Farming during 2018 to 2020. The objectives of the study are to develop low cost filters and to test the developed system in the field for efficiency in terms of pressure drop throughout discharge and quality of output. It was observed that the discharge from the filter increases as the time increases. Pressure drop and head loss in the filter system increases with flow rate. Filtration efficiency is a percentage of sand particles divided by the TSS removed by the filter. Efficiency of the filter increased from 25% to 64% (double chamber filter) and 23% to 62% (single chamber filter) with flow range of 5 m3/h to 30 m3/h. As flow rate increases, soil particles retained and efficiency of the filter increased with increase in head loss. Filter materials and screen filter removed the sand particles effectively. Uniformity coefficient of 0.95 was observed in single chamber filter which is suitable for small farm application.

scholarly journals PORTABLE SAND FILTER FOR SMALL DRIP IRRIGATION SYSTEMS

Irriga ◽  
2018 ◽  
Vol 21 (1) ◽  
pp. 90
Author(s):  
Cleomar Ferreira de Oliveira ◽  
Marconi Batista Teixeira ◽  
Adriana Ramos ◽  
Renato Moreira da Silva ◽  
Pedro Henrique Pinto Ribeiro ◽  
...  
Keyword(s):  
Water Quality ◽  
Flow Rate ◽  
Drip Irrigation ◽  
Low Cost ◽  
Maximum Flow ◽  
Head Loss ◽  
Effective Control ◽  
Trickle Irrigation ◽  
Irrigation Systems ◽  
Sand Filter

PORTABLE SAND FILTER FOR SMALL DRIP IRRIGATION SYSTEMS  CLEOMAR FERREIRA DE OLIVEIRA1; MARCONI BATISTA TEIXEIRA2*; ADRIANA RAMOS3; RENATO MOREIRA DA SILVA4; PEDRO HENRIQUE PINTO RIBEIRO5 E JOSÉ ANTÔNIO FRIZZONE6 1 Engenheiro Agrônomo, Prof. Dr. IFMinas Gerais - Campus Muzambinho, MG.2 Engenheiro Agrônomo, Prof. Dr. IFGoiano - Campus Rio Verde, GO. *E-mail: [email protected] Engenheira Agrônoma, Profa. Dra. Universidade Estadual de Santa Cruz – Ilhéus, BA.4 Engenheiro Agrônomo, Doutor, Departamento de Engenharia de Biossistemas, LEB - ESALQ/USP, Piracicaba - SP.5 Tecnólogo em Irrigação e Drenagem, Doutorando, Departamento de Engenharia Rural, UNESP/FCA, Botucatu, SP.6 Engenheiro Agrônomo, Prof. Titular, Departamento de Engenharia de Biossistemas, LEB - ESALQ/USP, Piracicaba - SP.  1 ABSTRACT Filters in drip irrigation systems are fundamental to ensure effective control of water quality and to reduce clogging of emitters. Current study aims at constructing a low cost portable sand filter for small localized irrigation systems (up to 1.0 ha) and at determining its head loss due to flow. Tests were carried out in the Hydraulic Laboratory of Biosystems Engineering Department of Agriculture School “Luiz de Queiroz”, University of São Paulo. Magnetic-induction Conaut Krohne model IFS 4000 w/6 with IFC 090 D signal convert of discharge, reading range between 0 and 90 m3.h-1 and 99% precision, was used for flow rate measurements. Pressure loss at each observation point was determined indirectly by two differential pressure gauges with a mercury column. A set of 20 flow readings was performed in three replications. Results showed that maximum filter discharge complied with ASAE guidelines and the cost of materials for manufacture of the filter was U$ 382.15. Linear mathematical model adequately describes the loss of pressure of the sand filter due to flow variation. Rates of minimum and maximum flow recommended range between 0.0257 m3.h-1 and 0.556 m3.h-1, and thus may satisfy small trickle irrigation projects. Keywords: Filtration, water quality, head loss, flow rate.

scholarly journals Effect of the Concentration of Sand in a Mixture of Water and Sand Flowing through PP and PVC Elbows on the Minor Head Loss Coefficient

2019 ◽  
Author(s):  
Piotr Wichowski ◽  
Tadeusz Siwiec ◽  
Marek Kalenik
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Cross Validation ◽  
Head Loss ◽  
Loss Coefficient ◽  
Number Range ◽  
Head Losses ◽  
Grain Sizes ◽  
Head Loss Coefficient ◽  
The Mathematical Model

The article presents the results of tests of minor head losses through PVC and PP elbows for a flow of water and mixtures of water and sand with grain sizes of up to 0.5 mm and concentrations of 5.6 g∙L-1, 10.84 g∙L-1, and 15.73 g∙L-1. The tests were carried out at variable flow velocities for three elbow diameters of 63, 75, and 90 mm. The flow rate, pressure difference in the tested cross-sections, and temperature of the fluids were measured and automatically recorded. The results of the measurements were used to develop mathematical models for determining the minor head loss coefficient as a function of elbow diameter, sand concentration in the liquid, and Reynolds number. The mathematical model was developed by cross validation. It was shown that when the concentration of sand in the liquid was increased by 1.0 g∙L-1, the coefficient of minor head loss through the elbows increased, in the Reynolds number range of 4.6∙104 &minus; 2.1∙105, by 0.3&minus;0.01% for PP63, 0.6&minus;0.03 % for PP75, 1.1&minus;0.06 % for PP90, 0.8&minus;0.01 % for PVC63, 0.8&minus;0.02 % for PVC75, and 0.9&minus;0.04 % for PVC90. An increase in Re from 5∙104 to 2∙106 for elbows with diameters of 63, 75 and 90 mm caused a 7.3 %, 6.8 %, and 6.0 % decrease in the minor head loss coefficient, respectively.

Challenges of Media Education Standards in Georgia

2017 ◽  
Vol 2 (2) ◽  
Author(s):  
Marine Vekua
Keyword(s):  
Working Conditions ◽  
Teaching Methods ◽  
International Standards ◽  
The Other ◽  
Historical Background ◽  
Journalism Education ◽  
Education Standards ◽  
Modern Media ◽  
The One ◽  
The Right

The main goal of this research is to determine whether the journalism education of the leading media schools inGeorgia is adequate to modern media market’s demands and challenges. The right answer to this main questionwas found after analyzing Georgian media market’s demands, on the one hand, and, on the other hand, differentaspects of journalism education in Georgia: the historical background, development trends, evaluation ofeducational programs and curricula designs, reflection of international standards in teaching methods, studyingand working conditions.

Russian experience in assessing informal employment indicators and their compliance with SDG indicators

2020 ◽  
pp. 1-18
Author(s):  
Elena Zarova ◽  
Dr Konstantin Laykam ◽  
Elvira Dubravskaya ◽  
Sergey Musikhin
Keyword(s):  
Sustainable Development ◽  
Sustainable Development Goals ◽  
International Standards ◽  
Informal Employment ◽  
Formal Sector ◽  
The Sustainable Development ◽  
Development Goals ◽  
The Russian Federation ◽  
The One ◽  
Main Components

This article describes on the one hand statistical methods for assessing informal employment based on the requirements as set by international standards. On the other hand it describes the potential of integrating various data sources to generate informal employment statistics. With as example official statistics of the Russian Federation, the authors show the features of applying the requirements of international standards. Methods are proposed for assessing informal employment in the formal sector of the economy, i.e. in enterprises that submit employment reports to the National Statistical Office. This phenomenon appears in the employment situation of many countries. However, there is no uniformity between countries in how they evaluate the application of the international standards in such assessment exercises. A theoretical model of informal employment is developed and validated based on statistical data published by international organizations. The validation focuses on assessing the causal relationships between informal employment indicators and the main components of the sustainable development goals. This analysis contributes to coordinated decisions on regulating informal employment and ensuring the achievement of the Sustainable Development Goals (SDGs).

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