Multioutlet Hydrants in Mediterranean Pressurized Irrigation Networks: Operation Problems and Hydraulic Characterization

[EN] Multioutlet hydrants as joint network infrastructure remain briefly addressed in the literature. Studies have always been limited to the individual treatment of the hydraulic components but not as a whole element. This study presents the main problems in the field of multioutlet hydrants within hydraulic infrastructure for pressure irrigation networks in Mediterranean agriculture. First, a field study with interviews was carried out in 30 water users associations (WUAs) between 2010 and 2018. Following this study, a laboratory test methodology was proposed to characterize this type of hydrant. Subsequently, four laboratory tests were performed on 12 multioutlet hydrants with different and common configurations found in irrigation networks: (i) head losses produced, (ii) global measurement precision in the multioutlet hydrant, (iii) blockage analysis in meters in vertical orientation, and (iv) hydrant behavior in response to hydraulic transients. The tests show that a horizontal configuration of the measuring elements with fewer than ten outlets and a suitable dimensioning of elements improve element maneuverability, instrument metrology, and irrigation emission uniformity. Finally, the importance of adequate design, dimensioning, and maintenance of the multioutlet hydrant devices is evidenced as a key point for the adequate management of collective pressure irrigation networks.Balbastre Peralta, I.; Arviza Valverde, J.; Palau, C.; González-Pavón, C.; Manzano Juarez, J. (2021). Multioutlet Hydrants in Mediterranean Pressurized Irrigation Networks: Operation Problems and Hydraulic Characterization. Agronomy. 11(11):1-15. https://doi.org/10.3390/agronomy11112240115111

Numerical Analysis of Woltman Meter Accuracy under Flow Perturbations

[EN] One of the unknowns in the instrumentation for water measurement is what degree of influence other hydraulic elements exert on the velocity profile and, consequently, on the measurement errors. In this work, the measurement errors of a horizontal-axis Woltman meter produced by a gate valve and by a butterfly valve in different hydraulic configurations were studied using a simplified numerical model. The gate valve was installed beside the meter and three pipe diameters upstream of the meter and were operated with closures of 75%, 50% and 25%, while the butterfly valve was installed at three pipe diameters upstream of the meter with closures of 0 degrees (open) and 30 degrees. The numerical model based on the rotor's torque balance equations and Computational Fluid Dynamics (CFD) was validated by experimental tests. According to the results, it was concluded that the proposed model is valid and capable of estimating the errors caused by the hydraulic fittings arranged next to the meter. In addition, it is evident that for the analysed operating range, both valves must be installed at least three diameters of straight pipe upstream of the meter.Palau, C.; Balbastre Peralta, I.; Manzano Juarez, J.; Moreira De Azevedo, B.; Bomfim, GV. (2019). Numerical Analysis of Woltman Meter Accuracy under Flow Perturbations. Water. 11(12). https://doi.org/10.3390/w11122622111

Caracterización y metodología de selección de inyectores Venturi en riego presurizado

[ES] El inyector para quimigación tipo Venturi tiene ventajas que hacen que sea un dispositivo bastante utilizado; no requiere energía eléctrica y es económico. Por el contrario, genera pérdidas de energía elevadas, afectando a las presiones en la instalación. Para una correcta caracterización de estos equipos deben relacionarse las presiones en los puntos de entrada, salida e inyección con los caudales principales e inyectados. Estas relaciones analíticas, que las introduce la norma de la Organización Internacional de Normalización (ISO 15873:2002), se pueden obtener de forma teórica; aunque es más recomendable que el fabricante establezca mediante ensayos de funcionamiento, el comportamiento real del inyector. Es oportuno que estas relaciones se proporcionen gráficamente, en la forma de nomogramas, para facilitar la asociación de las variables implicadas y la posterior selección de un modelo o clase concretos bajo una tipología de montaje. Así, para que esta selección sea adecuada es necesario también el conocimiento preciso de las subunidades de riego que alimenta y el programa de fertilización de la explotación.[EN] Venturi-type chemigation injectors are widely used due to their advantages: they do not require electric power and are cheap to operate. However, they also generate considerable energy losses which affect the pressure in the system. The correct characterization of these systems requires pressures to be correctly set at the inlet, injector and outlet points in relation to main and injected solution flows. These analytical relationships, as described in the International Organization for Standardization¿s standard ISO 15873:2002, can be obtained theoretically, although it is recommended that the manufacturer should determine the real behavior of the injector by operational tests. These relationships should also be provided graphically in the form of nomograms in order to facilitate the association of the variables involved and the subsequent selection of a specific model or class and type of assembly. In order to make the right choice, it is also necessary to have precise information on the irrigation sub-units that it feeds and the grower¿s fertilization program.Extraído parcialmente de la Tesis del primer autor, con el apoyo financiero de la Universitat Politècnica de València y del Centro Valenciano de Estudios del RiegoManzano Juarez, J.; Palau, C.; Moreira De Azevedo, B.; Do Bomfim, GV.; Vasconcelos, DV. (2018). Characterization and selection method of Venturi injectors for pressurized irrigation. Revista Ciência Agronômica (Online). 49(2):201-210. https://doi.org/10.5935/1806-6690.20180023S20121049

Design and installation alternatives of Venturi injectors in drip irrigation

[ES] En la Universitat Politècnica de València, Valencia, España (39°29¿ N; 0°23¿ W; 20 m), ha sido estudiado el funcionamiento de cuatro prototipos de inyector Venturi y tres formas de instalación distintas. El funcionamiento se ha analizado bajo diversos parámetros, como pérdidas de carga, relación de caudales y rendimiento. Las formas de instalación analizadas han sido: sin inyección y con inyección y presiones negativas o positivas en la garganta. Las presiones se establecieron entre 10 y 40 m.c.a. A partir de los datos experimentales han sido procesados utilizando técnicas de regresión múltiple y análisis de la varianza. Con ellas, fue posible, a través de la integración de geometrías en función de los diámetros, caudales y presiones, obtener expresiones para prever la pérdida de carga o el caudal inyectado. Se pone de manifiesto que la relación de caudales y el rendimiento son mayores cuanto mayor es el diámetro de la aspiración y empeoran al reducirse el diámetro de la garganta, siendo estas las dimensiones que más condicionan la inyección. También, puede afirmarse que la pérdida de carga, para un mismo caudal inyectado, es inferior si la operación se realiza con presiones positivas que con presiones negativas. La relación de caudales o el rendimiento también proporcionan valores más elevados bajo esta forma de instalación propuesta.[EN] The performance and installation alternatives of four Venturi injector prototypes were studied at Universitat Politècnica de València, Valencia, Spain (39°29¿ N; 0°23¿ W; 20 m). This device performance was studied under several parameters such as head loss, relation of flows and injection efficiency. The installation configurations analyzed were: without the injection of nutrients solution and with the injection either having negative or positive pressure at the Venturi throat. The inlet pressures were established between 10 and 40 m.w.c. The experimental data has been processed using multiple stepwise regression techniques and analysis of variance (ANOVA). Moreover, geometry integration versus diameters, flows and pressures is used to obtain some equations for predicting the head loss and injected flow. The results of the present study showed that the relation between flows and injection efficiency were better when the diameter of inlet nutrient line increases and become worse when decreases the diameter of the Venturi throat. Accordingly, these dimensions become very important in the design prototype and installation configuration. Furthermore, after the analysis of laboratory experiments it can be concluded that head losses, at the same injected flow, were lower if the injection was carried out with positive pressures at the throat than in the case of negative pressures. Also in this case, the relationship between flow rates and injection efficiency leaded to a good performance of the proposed installation.Manzano Juarez, J.; Palau, C.; Moreira De Azevedo, B.; Do Bomfim, G.; Vasconcelos, DV. (2015). Diseño y alternativas en la instalación de inyectores Venturi en riego localizado. Revista Ciencia Agronomica. 46(2):287-298. doi:10.5935/1806-6690.20150008S28729846

Measurements of differential production cross sections for a Z boson in association with jets in pp collisions at root s=8 TeV

Peer reviewe

Charged-particle nuclear modification factors in PbPb and pPb collisions at √=sNN=5.02 TeV

The spectra of charged particles produced within the pseudorapidity window |η| < 1 at √ sNN = 5.02 TeV are measured using 404 µb −1 of PbPb and 27.4 pb−1 of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0.5 < pT < 400 GeV in pp and 0.7 < pT < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, RAA, is measured in bins of collision centrality. The RAA in the 5% most central collisions shows a maximal suppression by a factor of 7–8 in the pT region of 6–9 GeV. This dip is followed by an increase, which continues up to the highest pT measured, and approaches unity in the vicinity of pT = 200 GeV. The RAA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, RpA, up to 120 GeV. For pT > 20 GeV, RpA exhibits weak momentum dependence and shows a moderate enhancement above unity

DIMSUB, a computer program for designing microirrigation subunits. Tool definition and case studies.

[EN] DIMSUB is a computer program to complement a decision support tool (DST) to effectively study different hydraulic design alternatives in microirrigation systems. We developed environments in Visual Basic for applications for Microsoft Excel (R) that allow specific step-by-step functions to be created for the design of irrigation subunits. Different alternatives can be considered, such as types of emitter, lateral and submain pipe sizes, different feeding points, irregular subunit shapes and topography slopes. Furthermore, specific uniformity criteria need to be considered to achieve efficient water applications and proper design systems. Lengths of run lateral and submain pipes, position of the hydrant connection, pressure head and head loss in pipes or pressure-compensating emitters can be assigned to evaluate the results and choose the best design alternative. This user-friendly tool to study hydraulic variables is expected to be a valuable aid for the decision-making process in designing irrigation systems. Some examples of practical cases under specific crop conditions to design drip irrigation subunits are given using DIMSUB.Palau, C.; Arviza Valverde, J.; Balbastre Peralta, I.; Manzano Juarez, J. (2020). DIMSUB, a computer program for designing microirrigation subunits. Tool definition and case studies. Scientia Agricola (Online). 77(3). https://doi.org/10.1590/1678-992x-2018-0184S77