Browsing by Author "Gogus, Mustafa"

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Citation - WoS: 0
Citation - Scopus: 0
Closure To "local Scour at Triangular Labyrinth Side Weirs Located on an Alluvial Channel" by Mustafa Tunc, Muhammet Emin Emiroglu, and Mustafa Gogus
(Asce-amer Soc Civil Engineers, 2023) Tunc, Mustafa; Emiroglu, Muhammet Emin; Gogus, Mustafa
Citation - WoS: 2
Citation - Scopus: 2
Critical Submergence for Single and Multiple Horizontal Intake Structures
(Springer Heidelberg, 2023) Gogus, Mustafa; Gokmener, Serkan; 6062
In this study, a series of experiments were carried out to investigate the variation of the critical submergence of air-entraining vortices with the related flow and geometric parameters at single and multiple horizontal intake structures. Three identical intake pipes were tested at a wide range of discharges with varying sidewall clearances under symmetrical and asymmetrical approach flow conditions. Experimental results indicated that increasing the number of intake structures in operation results in a more complicated flow pattern in front of the intake structures due to the mutual effects of the intakes on each other. Therefore, critical submergence values are higher for multiple intake structures than those of single water intake structures for a given Froude number. Dimensionless empirical equations were derived for each single, double and triple unit operation to calculate the critical submergence as a function of relevant flow and geometric parameters, and they were compared with the related equations available in the literature. These equations can be used to determine sufficient submergence to avoid air-entraining vortices at single and multiple horizontal intakes within the ranges of dimensionless parameters tested in this study.
Citation - WoS: 6
Citation - Scopus: 8
Determination of hydraulic characteristics of flow over a triangular sectioned weir by using experimental and numerical modeling
(Univ Tehran, Danishgah-i Tihran, 2021) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa; 6062
The spillways of hydraulic structures transfer excessive water from dam reservoir to the downstream in a safe and controlled manner. A labyrinth or triangular weir is a flat spillway folded in plain view. The labyrinth weirs provide an increase in crest length for a given channel width and increase the flow capacity for a given weir load. As a result of the increased flow capacity, the labyrinth and triangular weirs require less space in the dam body than the flat weirs. In this study, experiments were carried out on the labyrinth weirs containing triangles of different heights and numbers by using 3 different weir heights (P=20cm, 30cm, and 40 cm) and 4 different weir shapes. Each experiment was repeated for 30 different discharge values. The effects of weir height and weir shape on the total head over the weir (H-T) and discharge (Q) were investigated. In addition, the numerical models of all experimental setups were created by ANSYS-Fluent program using Computational Fluid Dynamics (CFD). By comparing the results obtained from the numerical models with the physical models, the accuracy of the numerical models was tested. According to the results, as the number of the triangles (N) of the weir increases, the discharge coefficient (Ca) decreases. The weir height (P) does not have a major effect on the discharge.
Citation - WoS: 8
Citation - Scopus: 9
Effect of Collars on the Downstream Movement of the Maximum Scour Depth Location Around Bridge Abutments and Piers
(Springer int Publ Ag, 2022) Kumcu, Serife Yurdagul; Kokpinar, Mehmet Ali; Gogus, Mustafa; 6062
A detailed investigation has been conducted to study the shift location of the point of the maximum scour depth for both bridge abutment-collar and pier-collar arrangements. In the present study, an experimental program has been conducted for abutment-collar arrangements and additionally, the data obtained from the literature for the pier-collar arrangements have been revisited and analyzed to complement the framework of this study. For the abutment-collar arrangements, a series of experiments under clear-water conditions were carried out for different abutment lengths with fixed values of collar location and collar width. For pier-collar arrangements, data used from the literature have been involved constant pier diameter with various collar sizes at various elevations. To describe the locations of these maximum scour depths, their coordinates with respect to the location of the abutment or the pier were obtained. Results from this investigation showed that when a collar placed on or below the bed level was used as a countermeasure against scouring, either on an abutment or on a pier, it was observed that the maximum scour depth was routed downstream of the bridge structure.
Citation - WoS: 0
Citation - Scopus: 0
Effect of Downstream Expansion of a Long-Throated Flume on Flow Properties
(Gazi Univ, 2021) Hatipoglu, Murat; Gogus, Mustafa; Ucar, Muhammed; 6062
Long throated flumes are widely used flow measurement devices that not requiring site-specific level to flow curves and therefore laboratory experiments. In this study, downstream expansion effect of the long throated flumes with rectangular cross section were analysed for the dimensionless parameters derived from Buckingham's pi theorem and some other known hydraulic quantities such as discharge coefficient, approach velocity coefficient, submergence ratio of the flow etc. Therefore, five downstream transitions with different expansion angles were tested. In each test, the critical depth y(c), the flow head at the depth measurement section h(1), minimum required energy dissipater length L-t and the head after hydraulic jump y(2) were measured for both modular and free flow conditions. The relation of hydraulic quantities of calculated dimensionless parameters with relevant parameters; modular limits, approach velocity coefficients and discharge coefficients etc. were graphed to represent the design relationships for long throated flumes.
Citation - WoS: 1
Citation - Scopus: 1
Effect of sediment properties on incipient motion of large solitary particles on fixed bed
(Emerald Group Publishing Ltd, 2021) Gogus, Mustafa; Haspolat, Emre; 6062
The effect of sediment properties such as shape, size, specific weight and packing (support) condition on the incipient motion of large solitary particles was systematically investigated. A series of experiments was conducted in a rectangular tilting flume with a smooth fixed (rigid) bed under uniform flow conditions. In each experiment, a thin fibreglass rectangular rod of height 1/5 or 1.5/5 of the height of the particle was placed just downstream of the particle to imitate the interaction of particles in rivers. Contrary to common belief and knowledge, it was found that the Shields parameter decreased as the dimensionless grain diameter increased for a given bed slope under rough turbulent flow conditions. Moreover, a larger shear stress was needed to start the motion of particles on steeper slopes for a given particle diameter. An increase in the ratio of the support height to particle height by 50% resulted in an increase in the dimensionless critical shear stress by almost six times for the same particle and relative roughness.
Citation - WoS: 2
Citation - Scopus: 2
Effects of Collars in Reducing Local Scour Depth Around Bridge Abutments Under Unsteady Flow Conditions
(Springer int Publ Ag, 2025) Gokmener, Serkan; Gogus, Mustafa; Altan-Sakarya, A. Burcu
In this experimental study, semi-circular end collars around semi-circular end abutments and rectangular collars around rectangular abutments were tested in order to investigate the efficiencies of the collars in reducing the local scour depth under unsteady-state clear-water approach flow conditions. Experiments were conducted in a rectangular sediment channel having a sediment pool filled with uniform sand as the bed material. Three different abutment lengths having constant widths were tested under three distinct successive flow intensities that were applied continuously for a duration of 2 h during each experiment. Varying sizes of collars were located at different elevations relative to the bed level. The effect of abutment length, collar width, collar elevation, flow intensity and temporal variation on local scour reduction performances of collars were tested. According to the experimental results, it can be stated that the application of collars around the semi-circular end and rectangular bridge abutments decreases the local scour depth by up to 72% and 51%, respectively. In addition, semi-circular end collars around semi-circular end abutments gave better results in reducing the scour depths than rectangular collars around rectangular abutments. Best collar performances were generally achieved for the largest collar width located around the bed level for semi-circular end abutments and below the bed level for rectangular abutments.
Citation - WoS: 1
Citation - Scopus: 3
Effects of collars on local scour around semi-circular end bridge abutments
(Emerald Group Publishing Ltd, 2023) Gogus, Mustafa; Daskin, Sueyla; Gokmener, Serkan
The occurrence of scour around bridge elements due to the transportation of bed material during flood events can cause serious structural damage and loss of life. Increased uncertainties in precipitation and runoff predictions due to climate change make this phenomenon more complex and dangerous. Bridge scour countermeasures should thus be more focused on decreasing scour formation around bridge elements. In this study, abutment scour under clear-water conditions with constant flow intensity was conducted and collars were tested as scour countermeasures around semi-circular end bridge abutments. The experimental study was performed in a rectangular channel with an almost uniform cohesionless bed material for 3 h with and without collars. Collars of various lengths located at different elevations around the abutments were tested to investigate the effect of collars on scour development. The results of the study showed that the scour depth decreased with increasing collar width and when the collar was placed below the bed level for a given abutment length. The results were compared with those of similar earlier studies to show the effect of abutment shape, size of the bed sediment and test durations on the development of scour depth around abutments.
Citation - WoS: 4
Citation - Scopus: 4
Estimation of Critical Submergence at Single Horizontal Intakes Under Asymmetric Flow Conditions
(Springer Heidelberg, 2022) Haspolat, Emre; Gogus, Mustafa; 6062
Air-entraining vortices are one of the serious hydraulic phenomena which can create various problems during the operation of intakes. Generally, air-entraining vortices start to form when the intake submergence is insufficient and less than a critical value. The purpose of the present study is to investigate the formation of air-entraining vortices and determine the critical submergences at single horizontal intake under asymmetrical approach flow conditions by conducting experiments with four different pipe diameters. In the experiments, various sidewall clearances with a series of discharges were tested for a given pipe diameter to examine the effect of dimensionless flow and geometric parameters on the critical submergence. Based on dimensional analysis, empirical equations were derived to predict critical submergence by performing regression analyses of relevant dimensionless parameters. Scale effect analysis was also carried out to investigate the effect of neglected flow parameters on the critical submergence in the application of model similitude law. A formula that makes it possible to transform model results into prototype results in the range of tested parameters was derived and compared with similar studies mostly based on existing installations. Eventually, it was pointed out that the result of the model study underestimates critical submergence compared to others due to the scale effects. Moreover, it was determined that critical submergences at intakes having asymmetrical approach flow conditions are higher than those of symmetrical approach flows.
Citation - WoS: 0
Citation - Scopus: 0
Experimental Study on the Interaction Between Bridge Pier and Abutment Concerning Clear-Water Local Scour
(Springer int Publ Ag, 2023) Akbulut, Omer Faruk; Kokpinar, Mehmet Ali; Gogus, Mustafa; 6062
Estimation of scour depth around bridge piers and abutments is essential for safety and economic design in alluvial rivers. Although local scour around bridge piers and abutments has been studied separately by a large number of investigators, there is limited research on the literature related to the interaction between these two structures. Hence, in this study, the aim is to investigate the interaction between bridge abutments and pier scours in detail. For this reason, bridge abutments of different lengths of La = 0.05, 0.10, and 0.15 m and a pier with diameter of D = 0.1 m were placed at various distances from each other in a long sediment channel and tested under clear-water flow conditions with constant flow intensity. All the important dimensionless parameters involved in the interaction phenomenon were derived from theoretical analysis, and the relationships between them were investigated. Analysis of the data showed that the presence of a pier in the flow medium in addition to an abutment has a certain amount of influence on the formation of scour holes around the structures. The influence of the abutment on the pier was more noticeable in the current study, particularly for longer abutments, leading to average increases of up to 20% in scour depth around the pier. The study's findings revealed that the presence of both a pier and an abutment in the flow medium exerted a discernible, unfavorable influence on the development of scour holes, particularly around piers.
Citation - WoS: 4
Citation - Scopus: 5
The Hydraulic Investigation of Harmonic Plan Weirs
(Elsevier Sci Ltd, 2024) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa
Existing dams and reservoirs need to be revised to meet safety standards. For the existing reservoirs where flood control is important and the maximum water level is limited, the best method to increase reservoir capacity is to build a labyrinth weir on the dam. In labyrinth weirs, the collision of two nappe flows produces nappe inter-ference, and this reduces the weir performance. In this study, the semi-circle weirs are placed in an open channel harmonically to increase the efficiency of the labyrinth weirs to make the areas more efficient and increase the flow capacity because of the nappe interference and to ensure the flow moving perpendicular to the weir as possible. In the experimental study of the asymmetrically placed circular weirs, 3 different weir heights (P = 20 cm, 30 cm and 40 cm) and 3 different labyrinth cycle numbers (N = 2, N = 3 and N = 4) were used. As a result of the experiments, although there was a 13 % decrease in the discharge coefficients (Cd) compared to the linear weirs, it provided a 57 % increase in the net crest length (Lnet). Discharge coefficient (Cd) is decreased 3.4 %, as the number of cycles (N) increases. As the weir height (P) decreases, Cd increases 7.5 % due to the vacuum effect.
Citation - WoS: 1
Citation - Scopus: 1
Hydraulics of circular bottom intake orifices
(Wiley, 2021) Gogus, Mustafa; Bulut, Muhammed; Ucar, Muhammed; 6062
In this study, the hydraulic characteristics of circular bottom intake orifices were investigated in a hydraulic model. The structure diverts the river-flow to a hydroelectric power plant through circular orifices located at the bottom of the channel. In the model, a series of circular holes of various diameters and locations at the bottom of a channel in the form of single and multiple holes were tested for different flowrates and screen angles (theta) to determine the flow diverting capacity of them. Discharges passing through orifices at known locations (x) and diameters (d) and screen slopes (theta) were measured and recorded along with the related main channel flow rates and depths (h). Using the dimensional analysis approach, an expression for the flow rate diverted from the main channel was derived as a function of related parameters, and their variations with each other were presented graphically and empirical equations were determined. Referring to the graphs and empirical equations, one can determine the discharge capacity of single and multiple intake orifices, which is important to calculate the amount of flow to be diverted from the main channel within the ranges of the related parameters used in this study.
Citation - WoS: 3
Citation - Scopus: 3
Local Scour at Triangular Labyrinth Side Weirs Located on an Alluvial Channel
(Asce-amer Soc Civil Engineers, 2022) Tunc, Mustafa; Emiroglu, Muhammet Emin; Gogus, Mustafa
The studies on labyrinth side weirs have received considerable attention in existing literature. A mobile bed, which causes significant morphological bed changes, can be induced by the side overflow weir. In this study, the local scour depths that occur near a triangular labyrinth side weir at a 90 degrees angle in a straight channel with an alluvial bed were experimentally examined under steady flow conditions with free overflow of the weir. Based on a dimensional analysis applied according to the parameters of the study, it was determined that dimensionless equilibrium scour depth is dependent on the approach flow intensity, dimensionless side weir crest height, dimensionless median grain size, dimensionless side weir opening, and dimensionless volumetric amount of upstream sediment feed under live-bed scour conditions. For different combinations of weir opening length and weir height, data for a set of 81 runs were obtained. The results show that an increase in weir crest height results in a decrease in dimensionless maximum scour depth. In the clear-water scour experiments, sediment deposits were observed downstream of the weir. In the live-bed scour experiments, the dimensions of the scours and sediment deposits that occurred upstream and downstream of the weir exhibited periodic changes. Good consistency was attained in the developed empirical equations between the calculated and measured values of the equilibrium scour depth.
Citation - WoS: 2
Citation - Scopus: 2
Local scour evolution around semi-circular end bridge abutment in quasi-unsteady condition
(Ice Publishing, 2022) Gokmener, Serkan; Gogus, Mustafa; 6062
In this experimental study, the temporal development of local scour is studied around semi-circular end bridge abutments under quasi-unsteady clear-water flow conditions in a rectangular sediment channel. A step-wise hydrograph of 6 h duration is used in the experiments. Six different abutment lengths having constant width, with uniform sand as bed material, were tested for three different successive flows - each applied continuously for 2 h. Bathymetry of the bed level was measured around the abutment every 15 min with the help of a measurement device to observe temporal development of the local scour around the semi-circular end abutment. Effects of the abutment length, flow intensity and time on the scour depths around semi-circular end bridge abutments, along with those at the front, upstream and downstream faces of the abutment, are also investigated and discussed. It is shown that the maximum scour depth always occurs at the front noses of the abutments compared with those at the upstream and downstream noses. A dimensionless empirical formula is derived to predict the scour depth at the front nose of the abutment as a function of related parameters. The results reveal that flow intensity is the most critical parameter in scour development.
Citation - WoS: 3
Citation - Scopus: 3
Numerical and experimental modelling of flow at Tyrolean weirs
(Elsevier Sci Ltd, 2021) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa; 6062
In this study, a small-scaled Tyrolean weir model was constructed in the laboratory environment and a series of experiments were conducted on it, for two different rack inclinations (theta(1) = 18 degrees and theta(2) = 25 degrees) and three different bar spacings (e(1) = 3 mm, e(2) = 6 mm and e(3) = 10 mm) for a range of upstream flow discharges. The flow rates passing through the racks and going downstream over the racks were measured. Empirical equations for the discharge coefficient and water capture capacity of the Tyrolean weirs were determined by applying dimensional analysis to the parameters involved in the phenomenon. The related dimensionless parameters were presented with graphs and empirical equations for discharge coefficients were derived, coefficient of determination R-2 of equations for theta(1) = 18 degrees and theta(2) = 25 degrees are found 0.838 and 0.825 respectively. According to results obtained from experimental data, C-d increases as the Froude number ((F-r)(e)) between bars increases and water capture capacity [(q(w))(i)/(q(w))(T)] of the racks decreases with increasing ((F-r)(e)). Also, a numerical model of the Tyrolean weir was generated by using Flow-3D software and it was shown that the results of the numerical analysis were very consistent with the physical model results at large bar spacing such as e = 10 mm. As the bar spacing (e) reduces, the success of the numerical model giving consistent results with physical model is decreasing.
Citation - WoS: 1
Citation - Scopus: 1
The Performance Of Water Jet Pumps And Their Applicatıon In Slurry Transportation
(Turkish Soc thermal Sciences Technology, 2023) Kokpinar, Mehmet Ali; Gogus, Mustafa; 6062
This present work is focused firstly on an experimental investigation for the optimum design of water jet pumps to be used in the hydrotransport of solid particles through pipeline systems. Experiments were conducted in a closed test loop using five types of jet pumps with various dimensions of the driving nozzle, suction nozzle, mixing chamber, and diffuser employing water as driving and suction fluid. The efficiency of each water jet pump element was analyzed and interpretations of results related to each water jet pump were made about the parts to be considered in the optimum design of a water jet pump. From the experimental results, the water jet pump having the optimum mixing chamber, suction nozzle, driving nozzle location, and cross-sectional dimensions produced a maximum efficiency of about 33%. In the second part of the study, the solid particle carrying capacity of water jet pumps in a pipeline system was studied under saltation, moving bed, and heterogeneous flow regimes by introducing seven different types of solid particles having various concentrations into the closed test loop. The effect of jet pumps on separating solid particles from flow in a region was investigated. A curved form of a by-pass system called the 'flow division unit' was added to the main pipeline system and through the flow division unit, then most of the solid particles in the flow were forced to flow towards the suction pipe of the jet pump. As a result of this, only water with very small particle concentrations passed through the centrifugal pumps, and in this way, the wear risk of the centrifugal pump was reduced considerably.