نوع مقاله : مقاله پژوهشی

نویسندگان

• سید زانیار نیک خواه ¹
• جواد احدیان ²
• سید محمود کاشفی پور ³
• سید محسن سجادی ²

¹ دانشجوی دکتری سازه های آبی، گروه سازه های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز، اهواز، ایران.

² دانشیار گروه سازه های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز، اهواز، ایران.

³ استاد گروه سازه های آبی، دانشکده مهندسی آب و محیط زیست، دانشگاه شهید چمران اهواز، اهواز، ایران.

چکیده

یکی از قدیمی ­ترین سازه ­های انحراف آب، آبگیر است. آبگیر جانبی یکی از روش‌های مناسب انحراف آب به دشت‌های مجاور است که موجب ایجاد جریان پیچیده­ای در ورودی آبگیر می­ شود. در این تحقیق، عملکرد دیوار جداکننده در دو فاصله (صفر  و  متری از ابتدای آبگیر) از دهانۀ آبگیر جانبی بر دبی ورودی به آبگیر جانبی بررسی شد. آزمایش‌ها در چهار دبی (40، 50، 60 و 70 لیتر بر ثانیه) و سه حالت بازشدگی دریچه (بسته، گشودگی 1 و گشودگی 2) اجرا شد. نتایج بررسی­ها نشان داد دیوار در فاصلۀ صفر متری نسبت به 1 متری تأثیر بیشتری بر عمق پایین‌دست دارد و در بسیاری از دبی‌ها باعث افزایش عمق پایین‌دست شده است. عمق بالادست تقریباً در همه آزمایش‌ها نسبت به حالت شاهد کاهش یافته که دلیل آن افزایش سرعت جریان در ورودی به محدوده دیوار است. بیشترین کاهش عمق بالادست (5/69- درصد) در دبی 40 لیتر بر ثانیه و گشودگی یک دریچه با دیوار در فاصله یک متری، و بیشترین افزایش عمق پایین‌دست (40/3+ درصد) در دبی 70 لیتر بر ثانیه و گشودگی یک دریچه با دیوار در فاصلۀ صفر متری رخ داد. بررسی سرعت جریان در سه نقطه (ابتدا، وسط و انتهای دیوار) نشان داد بیشترین سرعت در ابتدای دیوار و کمترین سرعت در میانۀ دیوار ثبت می‌شود. در دبی 40 لیتر بر ثانیه، درصد کاهش سرعت در سه سناریوی مختلف بین 3/1 تا 26/5 درصد متغیر است. اثر دیوار جداکننده بر دبی آبگیر نیز مثبت است و در هر دو حالت فاصله کارگذاری، درصد دبی ورودی به آبگیر نسبت به حالت شاهد افزایش یافته است. دیوار با فاصلۀ صفر متری عملکرد بهتری داده است و بیشترین افزایش دبی به آبگیر (14/97 درصد) در دبی 70 لیتر بر ثانیه، فاصلۀ صفر متری و گشودگی دو دریچه (جریان آزاد) مشاهده شده است.

کلیدواژه‌ها

• الگوی جریان
• عمق جریان
• آبگیر جانبی
• دیوار جداکننده

موضوعات

• مهندسی رودخانه

عنوان مقاله [English]

Comparative Evaluation of Splitter Wall Placement at Two Distances from a Lateral Intake on Diverted Discharge

نویسندگان [English]

• Seyed Zanyar Nikkhah ¹
• Javad Ahadiyan ²
• Seyed Mahmood Kashefipour ³
• Seyed Mohsen Sajjadi ²

¹ PhD Candidate of water structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran

² Associate professor, Department of water structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran.

³ Professor, Department of water structures, Faculty of Water and Environmental Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran

چکیده [English]

Extended Abstract
Introduction
Lateral intakes are widely used for diverting water from rivers to irrigation, municipal, and industrial systems. However, the complex flow pattern that develops near the intake entrance may reduce diversion efficiency and alter the hydraulic characteristics of the approaching flow. Among the structural measures proposed to improve intake performance, splitter walls installed parallel to the main flow have attracted attention because they can modify the flow pattern with limited changes to the channel geometry. Although previous studies have investigated various approaches to improve the hydraulic performance of lateral intakes, the effect of the splitter wall-to-intake distance has received limited attention. Therefore, this study experimentally evaluates the effect of two splitter wall-to-intake distances (L = 0 and 1 m) on upstream and downstream flow depths, flow velocity at three locations along the wall, and diverted discharge under different approach discharges and downstream gate-opening conditions.
 Methodology
Experiments were conducted in the Hydraulics Laboratory of Shahid Chamran University of Ahvaz using a physical model of a main channel with a lateral intake oriented at 79° relative to the main-channel flow direction. Four approach discharges (40, 50, 60, and 70 L/s) and three downstream gate-opening conditions (closed, one gate opened, and two gates opened) were examined. A splitter wall installed parallel to the main flow was tested at two splitter wall-to-intake distances (L = 0 and 1 m), together with a reference case without the wall. Flow depths upstream and downstream of the splitter wall were measured, while flow velocity was recorded at three locations along the wall (upstream end, midpoint, and downstream end) using an electromagnetic current meter (ACM3-RS). The diverted discharge into the lateral intake was determined using a rectangular sharp-crested weir installed at the intake outlet. Percentage changes in flow depth and diverted discharge were calculated relative to the corresponding reference case without the splitter wall.
 Results and Discussion
Installing the splitter wall altered the hydraulic characteristics of the approaching flow compared with the corresponding reference case without the wall. In almost all experimental conditions, the upstream flow depth decreased, mainly because of local flow acceleration near the upstream end of the splitter wall. The greatest reduction in upstream flow depth, 5.69% relative to the corresponding reference case, occurred at an approach discharge of 40 L/s, with one gate opened and the splitter wall installed at L = 1 m. In contrast, the downstream flow depth generally increased after the splitter wall, reflecting a redistribution of the flow profile along the main channel. This increase was more pronounced for L = 0 m. The maximum downstream flow-depth increase, 40.3% relative to the corresponding reference case, occurred at an approach discharge of 70 L/s, with one gate opened and the splitter wall installed at L = 0 m. Flow velocity measurements at the upstream end, midpoint, and downstream end of the splitter wall showed a clear longitudinal variation along the wall. The highest velocity was recorded at the upstream end, whereas the lowest velocity occurred at the midpoint. At an approach discharge of 40 L/s, the reduction in velocity between the measurement locations ranged from 3.1% to 26.5%, depending on the splitter wall-to-intake distance and gate-opening condition. The velocity increased again toward the downstream end of the wall, consistent with the observed increase in flow depth downstream of the wall.
The splitter wall also improved the diversion performance of the lateral intake. Compared with the corresponding reference case without the wall, the diverted discharge increased for both splitter wall-to-intake distances under the tested gate-opening conditions. The L = 0 m configuration generally produced higher diverted discharges than the L = 1 m configuration. The maximum increase in diverted discharge, 14.97% relative to the corresponding reference case, was observed at an approach discharge of 70 L/s, with the splitter wall installed at L = 0 m and two downstream gates opened under free-flow conditions. Overall, the results show that the splitter wall-to-intake distance affects the hydraulic characteristics of the main-channel flow and the amount of water diverted into the lateral intake.
 Conclusions
The experimental results showed that installing a splitter wall modified the flow-depth and velocity distributions along the main channel and increased the diverted discharge compared with the corresponding reference cases without the wall. The L = 0 m configuration generally provided greater diversion improvement than L = 1 m. The maximum increase in diverted discharge was 14.97%, observed at an approach discharge of 70 L/s with two downstream gates opened under free-flow conditions. These findings suggest that positioning a splitter wall close to the lateral intake may provide a simple hydraulic measure for improving diversion performance. However, further investigation of construction requirements, field applicability, and scale effects is needed before its practical implementation can be assessed.
 Conflict of Interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
 Funding
The authors received no financial support for the research, authorship, and publication of this article.
 Data Availability
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
 Author Contributions
S.Z.N : Software, Validation, Formal Analysis, Investigation, Data Curation, Writing-original draft, Visualization. J.A: Conceptualization, software, Validation, Investigation, Resources, Writing-review and editing, Visualization, Supervision, Project administration, Funding acquisition. S.M.K: Methodology, Validation, Investigation, Visualization. S.M.S: Validation, Investigation, Visualization.
Acknowledgment
The authors express their gratitude to all individuals who assisted in the advancement of this research, particularly the professors and staff of the Department of Hydraulic Structures, Faculty of Water and Environmental Sciences, Shahid Chamran University of Ahvaz.

کلیدواژه‌ها [English]

• Lateral intake
• separator wall
• flow depth
• flow pattern