One of the causes of the destruction or damage of many bridges in the world is the local scour around the bridge piers. Accordingly, research on effective factors on the scouring pattern around the bridge piers is a necessity. In this study, the parameters of the scour hole created around rectangular piers, such as the depth, area and volume of the scour hole, and the effects of increasing the rectangular pier’s length-to-width ratio and its skewness angle towards the banks on scour hole parameters, bed topography changes and the downstream straight path in a 180? sharp bend has been investigated. The results showed that in a 180? sharp bend, the length of the rectangular pier should be at least 3 and at most 5 times its wi
Nowadays, the major concerns to meeting the growing demand for water and the sustainable development goals in the nation are these facts that a relatively large area of the nation is in arid and semi-arid regions and the annual aridness continuously increases. Generally, however, the solution to this concern could be tackled by further research on the river engineering issues and providing appropriate solutions for better use of the river water resources. One of these solutions is to minimize the sediment while diverting water away from its natural path into an intake, as the sediment transport through the intake is a serious problem. However, 3D flow conditions in river divisions makes it difficult to characterizing the flow of water and s
In this paper, the effect of increase collar thickness has been investigated by considering other parameters affecting the flow pattern around the oblong bridge pier located at 90 degrees from the 180 degrees bend constant. Data acquisition was performed using the Vectrino 3D velocimeter. The leveling of the collar in both tests is constant and 0.4 times the pier diameter above the initial bed surface. The flow conditions were close to the motion threshold and bed balanced. The results showed that with an increase in the thickness of the collar by a factor of 4, the barrier surface is located in the flow path and the flow is deviated to the bed by colliding with the edge of the collar. This flow deviation that was due to the increase the c
In this paper, the effect of increase collar thickness has been investigated by considering other parameters affecting the flow pattern around the oblong bridge pier located at 90 from the 180 bend constant. Data acquisition was performed using the Vectrino 3D velocimeter. The leveling of the collar in both tests is constant and 0.4 times the pier diameter above the initial bed surface. The flow conditions were close to the motion threshold and bed balanced. The results showed that with an increase in the thickness of the collar by a factor of 4, the barrier surface is located in the flow path and the flow is deviated to the bed by colliding with the edge of the collar. This flow deviation that was due to the increase the collar thickness,
The peak flood discharge from basin is one of important informations required for planning of the water resources projects. In many cases long term data of annual runoff are not available at a particular site. However meteorological data such as the peak rainfall and other informations regarding basin characteristics are generally available.In this paper the available data from several sub-basins of Halil Rood basin (Iran) have been used to verify the existing empirical relationships for peak flood discharge estimation. Further, using the available data a simple deterministic model for estimation of peak flood discharge for Halil Rood basin has been developed. It was found that important parameters such as basin area, rainfall, slope of bas
Two main goals of water diversion away from rivers are sediment control and water supply with minimum sediment. These goals are commonly accomplished by using some hydraulic structures such as: sills, spur dikes and submerged vanes. These structures make changes in the pattern of flow and consequently the bed topography that lead to control of sediment entry into an intake. Despite their important role in sediment control, the results of previously published works indicate that in some cases these structures can cause substantial scour near the bank at the downstream of the intake on the main channel that may seriously jeopardize the stability of the bank in this area.Using six layouts this report presents the results of an experimental stu
Scouring around the bridge's piers is one of the major causes of serious damage to the bridge pier. A laboratory modelling method has been utilized in this research to study the effect of level and thickness of collar on scouring around the pier. The experiments were carried out in a channel with a 180 bend and a relative curvature radius equal to 2. This channel is composed by the straight upstream-and downstream-directed paths, respectively, 6.5 and 5.1 m long and 1 m wide. All experiments were conducted with a constant discharge capacity equal to 0.07 m 3⁄ s. The obtained results indicated that the installation of the collar at the initial bed surface and 0.4 pier width under the initial bed level with thickness of 0.12 and 0.06 pier w
سرریز غیر خطی کلیدپیانویی در مقایسه با سرریز خطی ضمن آبگذری بیشتر، ساختاری به نسبت ساده دارد و سازهای اقتصادی است. مزیتهای دیگر سرریزهای کلیدپیانویی عبارتند از: دبی بر واحد عرض عبوری از سرریز را تا 100 مترمکعب بر ثانیه بر متر افزایش میدهند، دبی عبوری از این نوع سرریزها حداقل 4 برابر سرریزهای معمولی (خطی) است، باعث افزایش ظرفیت مخزن میشوند و از لحاظ اقتصادی مقرون به صرفهتر بوده و هزینه نگهداری کمتری دارند. این ویژگ?
Introduction: The newest type of nonlinear weirs is the Piano key weir. This weir significantly increases the discharge, has a relatively simple structure, and is an economic structure. Various studies have been conducted to evaluate the factors affecting the discharge and optimization of this type of the weir. The purpose of this study was to modify the type A Piano key weir for better performance and discharge coefficient, and ventilation at the outlet. In this research, by applying changes such as a triangular nose at the entrance and a semicircular crest in the outlet of the A-type Piano key weir, its performance has been studied numerically by Flow-3D software.Methodology: The experiments were conducted in a laboratory channel with a l
One of the main causes of damage to dams, especially earth dams is the overtopping which may cause huge human losses and financial damages. Fuse plug is used as a safety valve to protect dams against catastrophic damages of overtopping. The increasing outbreak of floods and their huge and sometimes irrecoverable damages has incentivized dam experts and designers for more studies on the most effective and economical spillway construction. The attempt is towards letting higher amounts of water run through spillways. One approach is using an auxiliary spillway beside the main spillway. Fuse plug can be used as an economical auxiliary or emergency spillway. Fuse plug structure consist of embankment body and pilot channel. Fuse plugs are designe
In this paper, the effects of the nondimensional parameters influencing the discharge coefficient of a side-combined structure located in a channel bend were studied using 288 experimental data. Experiments were conducted in a rectangular recirculating U-shaped channel (0.6 m width and 0.7 m height) for different discharges and depths of flow in the channel. The effects of approach Froude number Fr , the ratio of the gate height to gate opening d/a, the ratio of the approach flow depth to gate opening h 1/a, and angle of the bend curvature α on the discharge coefficient under subcritical flow conditions are investigated. It was found that the flow diversion by a side-combined structure leads to a
The peak flood discharge from basin is one of important informations required for planning of the water resources projects. In many cases long term data of annual runoff are not available at a particular site. However meteorological data such as the peak rainfall and other informations regarding basin characteristics are generally available.
Labyrinth weir is one of the approaches to increase the discharge capacity. An arced configuration improves the orientation of the labyrinth weir cycles to the approach flow and increases the weir crest length for a given width. In this study, the effects of the entrance flow conditions on the hydraulic performance of the arced labyrinth weirs is studied experimentally. The effects of the angle between the entrance channel walls (Θ′) on the discharge coefficient and the efficiency are investigated for different values of the headwater ratio (Ho/P), the downstream sidewall angle (α), and the weir arc angle (Θ). Experiments were conducted in a recirculating flume which is 10 m long, 2 m wide, and 0.9 m deep at Tarbiat Modares University.
Labyrinth weirs can increase the flow discharge capacity for a specific head and width by increasing the weir length. This paper studies the flow behavior of labyrinth weirs using Flow-3D? software. The main goal is to evaluate the capability of the response surface methodology (RSM), especially central composite design (CCD), to describe the performance of labyrinth weirs. Traditional and RSM-CCD methodologies are applied using experimental data of previous researchers and numerical data of the present study, respectively. Results show that RSM-CCD can produce an acceptably accurate model for the discharge coefficient of labyrinth weirs with only a small fraction of the data required for the traditional model. In addition, the discharge co
The fuse plug is used as a safety valve to protect the dam from catastrophic failurs caused by overtopping flow. In this experimental study, using a series of experimental tests, the effect of plug fuse washout on the outflow discharge from the dam reservoir due to change the width and depth of the pilot channel has been investigated. The important point in this study is to be kept constant water level during the overtopping flow and the failure of the structure for the more similarity of this process to reality. The results of this experimental study are the outflow hydrograph resulting from the overtopping flow the change in width and depth of the pilot channel. Also, the effect of changes in the outflow discharge more dependent on the de
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