İnşaat Mühendisliği Bölümü

Permanent URI for this communityhttps://hdl.handle.net/20.500.12416/17

Browse

Now showing 1 - 9 of 9

Citation Count: Taştan, K., Yıldırım, N. “Effect of dual pipe intakes dimensions and positions on critical submergence”; ICOCEM 4. International Conference on Civil and Environmental Geology and Mining Engineering, Trabzon-Turkey, 2019.
Effect of dual pipe intakes dimensions and positions on critical submergence
(2019) Taştan, K.; Yıldırım, Nevzat; 12654
Citation Count: Taştan, K., Yıldırım, Nevzat. "Effect of intake entrance geometry on the critical submergence", IV. ECOCEE Eurasian Conference on Civil and Environmental Engineering İstanbul 17-18 June 2019.
Effect of intake entrance geometry on the critical submergence
(2019) Taştan, K.; Yıldırım, Nevzat; 12654
Citation Count: Taştan, Kerem; Koçak, Peli̇n Pınar; Yıldırım, Nevzat (2016). "Effect of the Bed-Sediment Layer on the Scour Caused by a Jet", Arabian Journal for Science and Engineering, Vol. 41, pp. 4029-4037.
Effect of the Bed-Sediment Layer on the Scour Caused by a Jet
(2016) Taştan, Kerem; Koçak, Peli̇n Pınar; Yıldırım, Nevzat; 12654
Scour caused by a water jet impinging the bedsediment layer is a significant concern for hydraulic engineers. Although several studies investigated the maximum scour depth on the non-cohesive bed-sediment layer, the effect of the bed-sediment layer’s thickness on the scour was not studied. This study investigated the effect of the thickness of the non-cohesive sediment layer at the canal bed on the depth of the scour caused by a water jet. The dimensionless parameters affecting the depth of the scour were obtained via dimensional analysis. Experiments were conducted on two different, non-cohesive bed-sediment layers at the bottom of a rectangular canal for different jet Froude numbers. Experimental results indicated that the depth of the scour increases with the thickness of the bed-sediment layer; this is because as the thickness of the sediment layer increases, the penetration depth of the air bubbles (dragged and enforced by the impinging water jet) through the sediment layer just under the scour hole increases. Due to the buoyancy force, as the air bubbles rise upward, they apply uplift forces and dynamic effects onto sediment particles, dislodging, suspending, and carrying the sediment particles away from the bed. If the thickness of the sediment layer is increased beyond a limiting value for a given flow condition, the maximum depth of the scour does not change (it remains almost constant). The effect of the thickness of the bed-sediment layer on the depth of the scour is present but not excessively large.
Citation Count: Taştan, Kerem; Yıldırım, Nevzat (2017). "Effective intake for critical submergence in the case of more than one intake", KSCE Journal of Civil Engineering, Vol. 21, pp. 1004-1008.
Effective intake for critical submergence in the case of more than one intake
(2017) Taştan, Kerem; Yıldırım, Nevzat; 12654
The available potential flow solution methods over-estimate the number of effective intake for the prediction of critical submergence in the case of multiple intakes of identical level without partition walls located on the longitudinal line of the canal, because they cannot establish an upper limiting value for the distance between the centers of the intakes. To address this, tests were conducted on dual intakes of identical level located on the longitudinal line of the canal in a cross-flow. In practice, by means of the chart obtained from the experimental results, one can determine the upper limiting value of the distance between the centers of dual intakes beyond which the effect of the intake on the critical submergence of the other intake is negligible. Such an intake is considered a non-effective intake and is disregarded in the prediction of critical submergence. In addition, the effective intake relating to multiple intakes sited in a still-water reservoir is explained.
Citation Count: Taştan, K., Yıldırım, N. (2018). Effects of intake geometry on the occurrence of a free-surface vortex. Journal Of Hydraulic Engineering, 144(4). http://dx.doi.org/10.1061/(ASCE)HY.1943-7900.0001439
Effects of intake geometry on the occurrence of a free-surface vortex
(ASCE-AMER Soc Civil Engineers, 2018) Taştan, Kerem; Yıldırım, Nevzat; 43229; 12654
Both the profile and orientation of an intake entrance basically determine the characteristics of the flow (especially the velocity distribution and therefore the hydraulically developed subsurface depressions) toward the intake. The profile and orientation of the intake affect (1)the process of accumulation and growth of vorticity (circulation) along the pathway axis of the swirling vortex from the free surface to the intake; (2)position of the pathway of the swirling-vortex filament; and (3)location of the point of entry of the free-surface or subsurface vortex at the entrance of the intake. Test results indicate that the intake-entrance profile has limited effects on the occurrence of the air-core vortex and critical submergence. Regardless of the profile of the intake entrance, one common physical mechanism exists for development of free vortices occurring at intake entrances of different profiles. It is proven that spherical sink surface sectors (SSSSs) are essential for the vortex to exist.
Citation Count: Taştan, Kerem; Yıldırım, Nevzat (2021). "Flow Rate along the Length of the Swirling Vortex Axis at an Intake", Teknik Dergi, Vol. 32, No. 4.
Flow Rate along the Length of the Swirling Vortex Axis at an Intake
(2021) Taştan, Kerem; Yıldırım, Nevzat; 12654
In this study, the characteristics of the flow in the region of swirling vortex are examined. The potential flow model based on the summing infinite number of spherical sinks along the vortex core is introduced to predict the flow field and the flow rate along the vortex axis. The flow towards the swirling vortex core has considerable effects on the radial velocity distribution within the ambient fluid flow region near the intake. The agreement between available test data relating to the radial velocity and the method introduced in this study is found to be satisfactory.
Citation Count: Taştan, K.; Yıldırım, N. (2023). "Improved Equations for the Profile of a Vertical Air-Core Vortex", KSCE Journal of Civil Engineering, Vol.27, No.5, pp.2030-2042.
Improved Equations for the Profile of a Vertical Air-Core Vortex
(2023) Taştan, Kerem; Yıldırım, Nevzat; 12654
The available formulas for the profile of a vertical non-air-entraining vortex are not practical because they involve unknown parameters and need measurements of the local viscous-core radii across the height of the air-core vortex. Also, these formulas can not be used for the air-entraining vortices. In the present study, the available formulas involving unknown parameters were further improved. Findings are as follows. 1) the magnitudes of the unknown parameters vary across the height of the profile of the air-core vortex and they are the function of the ratio of the height of the air-core vortex to the submergence of the intake; 2) simple charts and formulas were obtained for the variations of the unknown parameters for the air-core vortices with and without an intake; 3) in lieu of the local viscous-core radius, the radius at the half-depth of the profile of the air-core vortex was used; 4) no laborious work of measurements are needed to determine the local viscous-core radii along the profile of the vortex; and 5) the improved formulas are in good agreement with available test data for the profiles of both the non-air-entraining and the air-entraining vortices with or without a vertically flowing downward intake.
Citation Count: Taştan, Kerem; Yıldırım, Nevzat (2021). "Occurrence of a swirling vortex without an intake", Gazi University Journal of Science, Vol. 34, no. 1, pp. 54-61.
Occurrence of a swirling vortex without an intake
(2021) Taştan, Kerem; Yıldırım, Nevzat; 12654
In this study, mechanisms that cause the occurrence of a swirling vortex without an intake are explained. There are more than one different reasons which may cause the occurrence of an aircore vortex or a swirling-vortex flow filament within an ambient fluid. An air-core vortex or a swirling vortex flow filament can also occur in an ambient fluid media without an intake provided that the coaxial subsurface depressions and thereby the imaginary subsurface spherical sink surface sectors are hydraulically developed by any means (such as rotation of the fluid mass of spherical sector-form, impinging or penetrating jet flow, continuously entering solid body or string etc.). Although studies related to occurrence of a swirling vortex in case of an intake can be found in available literature, there are currently no studies which explains the occurrence mechanisms of a swirling vortex without an intake in detail. In this study, it is showed that the causes for the occurrence of the air-core vortex or the swirling vortex filament can be different but the main mechanism of development of the air-core vortex or the swirling vortex filament is identical for all cases. © 2021, Gazi Universitesi. All rights reserved.
Citation Count: Taştan, Kerem; Yıldırım, N. (2018). "Su alma ağzı giriş şeklinin hava girişli çevrinti üzerindeki ölçek etkisi", Gazi Üniversitesi Fen Bilimleri Dergisi Part C: Tasarım ve Teknoloji, Vol.6, No.3, pp.492-506.
Su alma ağzı giriş şeklinin hava girişli çevrinti üzerindeki ölçek etkisi
(2018) Taştan, Kerem; Yıldırım, Nevzat; 12654
Su alma ağzı giriş şekli, ağız üzerinde su yüzeyinde oluşabilecek hava girişli çevrintinin karakteristiklerini belirlediğinden ağza ait kritik batıklık üzerinde bazı etkilere sahiptir. Bu etkiler hız dağılımı etkisi ve çevrintiyi besleyen ağız debisi etkisi olarak adlandırılabilir. Bu çalışmada 6 farklı ağız giriş şekline (daire, kare, dikdörtgen, eşkenar dörtgen, eşkenar üçgen, yıldız) ve 40 cm2 ve 100 cm2 olmak üzere iki değişik kesit alanına sahip toplam 12 adet su alma yapısına ait kritik batıklık ve kritik batıklığı etkileyen boyutsuz parametreler (su alma yapısına ait Froude, Reynolds ve Weber sayıları) durgun su ortamında deneysel olarak incelenmiştir. Deney sonuçları neticesinde ağız giriş geometrisinin kritik batıklık üzerinde bir boyut etkisine sahip olduğu görülmüştür. Bu nedenledir ki, her bir farklı ağız giriş geometrisi ve akım şartı, kritik batıklık açısından kendine özgü özellikler taşır. Aynı ağız debisinde farklı su alma ağzı giriş şekillerinin kritik batıklık üzerindeki etkisi ise debi değerine göre değişim göstermektedir.

Browse

Browsing İnşaat Mühendisliği Bölümü by Author "12654"