196,020 research outputs found
Closure to "Experimental Study of Central Baffle Flume" by F. Lotfi Kolavani, M. Bijankhan, C. di Stefano, V. Ferro, and A. Mahdavi Mazdeh
No full textThis is a Closure of the discussions on the paper “Experimental Study of Central Baffle Flume”
by F. Lotfi Kolavani, M. Bijankhan, C. Di Stefano, V. Ferro, and A. Mahdavi Mazde
Closure to "experimental Modeling of Submerged Pivot Weir" by M. Bijankhan and V. Ferro
No full textThis paper is a Closure to “Experimental Modeling of Submerged Pivot Weir”
Experimental Modeling of Submerged Pivot Weir
No full textAn inclined rectangular overflow structure, also called a pivot weir, consists of a rectangular plate, angled downstream from the vertical, that can be used as an upstream water level control device. A pivot weir is submerged when the upstream water level is influenced by the downstream flow depth. In this paper, to investigate factors influencing submerged flow conditions, an extensive experimental program including 251 experimental trials was carried out using weir inclination angles of 39.6°, 53°, 85°, and 90° and weir heights ranging from 0.263 to 0.312 m. A formula to distinguish between free and submerged flow conditions was developed using the Π theorem of dimensional analysis and the incomplete self-similarity (ISS) theory, and the submergence threshold curve was calibrated by the measurements carried out in this study. Employing a similar theoretical procedure (dimensional analysis and ISS theory), the tailwater depth for which a downstream standing wave starts and a stage-discharge relationship for submerged conditions also were developed. A comparison with the submerged stage-discharge formula proposed by the United States Bureau of Reclamation revealed that the proposed method could be more accurate for the entire operating range and conditions evaluated
Assessing Stage-Discharge Relationships for Circular Overflow Structure
No full textCircular overflow structures are used in irrigation and drainage networks as water measuring structures. Different approaches can be found in the literature to formulate the stage-discharge relationship of the circular weir. They are mainly categorized in three groups: (1)methods trying to simplify the complex elliptic integrals coming from the theoretical discharge equation; (2)methods that use the orifice formula and a discharge coefficient specific for the circular weir; and (3)approaches using dimensional analysis and Buckingham's Theorem. In this study, a nondimensional stage-discharge formula was obtained using Buckingham's Theorem to define the flow over the sharp-crested circular weir. Then the current available methods and experimental data from the literature were employed to calibrate the theoretically deduced stage-discharge relationship. The effect of the approach channel on the stage-discharge formula was also investigated using the experimental data available in the literature. Finally, the performances of different stage-discharge relationships are discussed and practical suggestions are provided
Discussion of "extraction of the flow rate equation under free and submerged flow conditions in pivot weirs with different side contractions" by N. Sheikh Rezazadeh Nikou, M. J. Monem, and K. Safavi
No full textThis paper is the discusison of the paper "Extraction of the flow rate equation under free and submerged flow conditions in pivot weirs with different side contractions" by N. Sheikh Rezazadeh Nikou, M. J. Monem, and K. Safavi
Discussion of "preliminary Study of Surface Hydraulic Jumps" by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam
No full textIn this paper the results of Preliminary Study of Surface Hydraulic Jumps” by S. Ahmed, Y. Ye, H. Liu, and N. Rajaratnam are discusse
Dimensional analysis and stage-discharge relationship for weirs: a review
No full textDeducing the weir flow stage-discharge relationship is a classical hydraulic problem. In this regard Buckingham’s theorem of dimensional analysis can be used to find simple and accurate formulas to obtain the rating curves of different weir types. At first, in this review paper the rectangular weir that is a very common hydraulic structure is studied. It is indicated that the crest shape, approach channel width, obliquity (angle between the weir crest and the direction normal to the flow motion) and vertical inclination (pivot weir) are the key-parameters affecting the flow over the rectangular weirs. The flow over the triangular, labyrinth, parabolic, circular, elliptical, and W-weirs are also studied using dimensional analysis and incomplete self-similarity concept. For all mentioned weirs the stage-discharge relationships are presented and the application limits are discussed. The results of this paper can be used and implemented by the irrigation and drainage network designers to simplify the procedure of weir design
Experimental study on triangular central baffle flume
No full textIn this paper the results of the experiments performed to study the flow through a Triangular Central Baffle Flume (TCBF) are reported. The investigated flume consists of a triangular baffle of the apex angle of 75° with a given base width. The theoretical stage-discharge formula was deduced by applying the Buckingham's Theorem and incomplete self-similarity hypothesis and was calibrated using the laboratory measurements carried out in this investigation. The proposed stage-discharge formula is characterized by a mean absolute relative error of 7.4% and 72% of the data points are in an error range of ±5%. The results indicate that TCBF flume is characterized by a flow capacity higher than that of a typical central baffle flume. Experimental observations show that the contraction ratio is a key parameter to distinguish between free and submerged flow regimes through a TCBF. Finally, to identify the flow condition, submergence threshold condition was formulated
Portable central baffle flume
No full textThis paper investigated the hydraulic characteristics of the triangular central baffle (TCB) flume. Laboratory tests were carried out to determine the flume dimensions. The field applicability of the proposed portable device was examined by on-farm installa-tion. According to the laboratory tests, when the contraction ratio, r, was less than 0.39, the flow capacity was not affected by the ratio between the flume’s floor height and the throat width. The laboratory analysis also showed that there was no significant effect of installing an entrance ramp on the stage-discharge rela-tionship for r<0.39, while the entrance ramp increased the discharge capacity for r>0.39. The stage-discharge curve obtained based on the laboratory tests was verified using field data. The results revealed that the proposed portable flume could be used accurately to determine the flow through an unlined ditch. Practical suggestions were proposed to determine the distinguish-ing condition curve
New theoretical solution of the outflow process with a weir with complex shape
No full textIn this paper, the outflow process of a weir with irregular shape is studied using the dimensional analysis and the incomplete self-similarity theory.
The new stage-discharge is theoretically deduced and it represents a comprehensive equation describing the weir outflow process for a full range of flow and geometric variables of the weirs.
Finally this stage-discharge relationship is calibrated using measurements available in literature
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