Trapez Kanallarda Savak Kapağı ve Savaklarla Enerji Azaltımının Deneysel ve Sayısal Analizi

Öz

In open channels, only one of the sluice gates or weirs is often used for regulation purposes to limit the acceleration of flow through the channel and to help reduce the forces around the water structures. When the sluice gates are used single, depending on the tail water depth and the gate opening, all cases might experience free or submerged flow conditions and hydraulic jump might occur at the downstream. In this case, it is possible to damage the submerged or semi-submerged structures in this area due to the high flow velocity and high hydraulic energy at the downstream of the gate. The combination of weirs and gates can be preferred both to preserve the stability of the river bottom and to prevent damage to structures such as submerged pipes and transmission lines stretching across cross-sectional direction. In this study, the variation of the flow characteristics in the channel and around the pipeline extending across the channel cross-section was investigated when varying cross-sections weirs with the sluice gate are used together. Experimental flow velocity and level measurements were carried out under different discharge conditions. These measurements were used to determine the boundary conditions of the computational fluid dynamics (CFD) software and to verify the flow property values obtained by CFD. After the verification, the velocity, pressure and specific hydraulic head values of the points that could not be measured experimentally with CFD software were also obtained. As a result of both experimental and numerical analysis, it has been seen that hydraulic head can be reduced significantly by using the gate and weir structures together. With the increasing discharge, the effect of the weir geometries on energy dissipation emerges clearly. By using the two structures together, both the water depth in open channels will be kept at the desired level and possible damage due to water forces acting on underwater structures will be prevented.

Anahtar Kelimeler

• Energy dissipation
• Open channel
• Velocity
• Sluice gate
• Weir

Experimental and Numerical Analysis of Energy Dissipation with Sluice Gate and Weirs in Trapezoidal Channel

Abstract

Açık kanallarda kanal boyunca akışın hızlanmasını sınırlamak ve su yapıları etrafındaki kuvvetleri azaltmaya yardımcı olmak için genellikle kapak veya savaklardan yalnız biri regülasyon amacıyla kullanılmaktadır. Savak kapakları yalnız kullanıldığında, kuyruk suyu derinliğine ve kapak açıklığına bağlı olarak serbest veya batmış akış koşulları meydana gelebilir ve mansapta hidrolik sıçrama oluşabilir. Bu durumda, kapağın mansabındaki yüksek akış hızı ve hidrolik enerji nedeniyle bu bölgedeki batık veya yarı batık yapıların zarar görmesi olasıdır. Kapak ve savakların beraber kullanımı, hem nehir tabanının stabilitesinin korunması hem de en kesit boyunca uzanan batık borular ve iletim hatları gibi yapılara zarar gelmemesi için tercih edilebilir. Bu çalışmada savak kapağı ile değişen en kesitli savaklar birlikte kullanıldığında kanalın ve kanal en kesiti doğrultusunda uzanan boru hattı etrafındaki akış özelliklerinin değişimi araştırılmıştır. Deneysel akış hızı ve su seviyeleri farklı debiler için ölçülmüştür. Bu ölçümler, hesaplamalı akışkanlar dinamiği (HAD) yazılımının sınır koşullarını belirlemek ve HAD ile elde edilen akış özelliği değerlerini doğrulamak için kullanılmıştır. Doğrulamanın ardından HAD yazılımı ile deneysel olarak ölçülemeyen noktaların hız, basınç ve özgül hidrolik enerji değerleri de elde edilmiştir. Hem deneysel hem de sayısal analizler sonucunda, kapak ve savak yapılarının birlikte kullanılmasıyla hidrolik enerjinin önemli ölçüde azaltılabileceği görülmüştür. Yüksek debilerde savak geometrisinin enerji kaybı üzerindeki etkisi açıkça görülmektedir. İki yapının birlikte kullanılmasıyla hem açık kanallardaki su derinliği istenilen seviyede tutulacak hem de su altı yapılarına etki eden su kuvvetleri nedeniyle olası hasarların önüne geçilecektir.

Keywords

• enerji azaltımı
• açık kanal
• hız

Kaynakça

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