مطالعه نظری و آزمایشگاهی سرریز جانبی ذوزنقه‌ای لبه‌گرد در شرایط رژیم زیربحرانی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 کارشناسی ارشد سازه های آبی، گروه مهندسی آبیاری و آبادانی دانشگاه تهران

2 عضو هیئت علمی گروه مهندسی آبیاری و آبادانی دانشگاه تهران

چکیده

سرریز جانبی یکی از انواع سازه­های انحراف آب است که به طور گسترده در شبکه­های آبیاری و زهکشی، کنترل سیلاب، سیستم فاضلاب شهری و کنترل سطح آب مورد استفاده قرار می­گیرد. جریان عبوری از سرریز جانبی از نوع جریان­ متغیر مکانی با کاهش بده می­باشد. در مطالعه حاضر با استفاده از مدل آزمایشگاهی و روش تحلیل ابعادی، به بررسی خصوصیات جریان عبوری از روی سرریز جانبی ذوزنقه­ای لبه­گرد واقع در کانال مستطیلی در شرایط جریان زیر بحرانی پرداخته شده است. برای ارزیابی ضریب بده و ارائه معادله بده سرریز جانبی در شرایط جریان آزاد، از تئوری سرریز معمولی با سه عمق مشخصه (عمق ابتدای سرریز، میانگین عمق ابتدا و انتها و عمق مرکزی) برای محاسبه هد سرریز استفاده شد. نتایج آزمایش­های تحقیق حاضر حاکی از آن است که ضریب بده سرریز جانبی ذوزنقه‌ای لبه‌گرد به عدد فرود جریان بالا‌دست، نسبت عمق جریان به قطر تاج سرریز و شیب جداره جانبی سرریز بستگی دارد. همچنین مقایسه نتایج با داده­های آزمایشگاهی نشان داد که روش عمق متوسط جریان با متوسط خطای برآورد برابر با 6/3 درصد بهترین جواب را برای تخمین ضریب بده ارائه می­کند، لذا این روش برای مقاصد عملی پیشنهاد می­شود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Theoretical and Experimental Study of Circular-Crested Trapezoidal Side Weir in Subcritical Flow Regime

نویسندگان [English]

  • Ramin Askari 1
  • Alireza Vatankhah 2
1 M.Sc., Irrigation and Reclamation Eng. Dept., University College of Agriculture and Natural Resources, University of Tehran, P.O. Box 4111, Karaj, 31587-77871, Iran.
2 Associate Professor, Irrigation and Reclamation Eng. Dept., University College of Agriculture and Natural Resources, University of Tehran, P.O. Box 4111, Karaj, 31587-77871, Iran.
چکیده [English]

Side weir is one of the diversion structures, which widely used in irrigation and drainage networks, flood protection, urban sewage systems and water level control. The flow over the side weirs is a typical case of the spatially varied flow with decreasing flow discharge. In this study, the flow characteristics over the circular-crested trapezoidal side weir located in rectangular channels is experimentally investigated under subcritical flow conditions. In this research, the conventional weir theory with three different reference depths (y1, yavg and ycenter) for computing the weir head was used to evaluate the proposed discharge coefficient and discharge equations. Based on the experimental results, the discharge coefficient is a function of upstream Froude number, the ratio of upstream flow depth to the crest diameter, and side slope of the weir. The comparison between the experimental data and computed results indicated that the conventional weir theory with the average flow depth as the reference depth with an average error of 3.6% is the best relationship for assessing the discharge coefficient. Thus, this method is suggested for practical purposes.

کلیدواژه‌ها [English]

  • Circular-crested trapezoidal side weir
  • spatially varied flow
  • discharge coefficient
  • subcritical flow
  • Free Flow

مراجع

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تحقیقات آب و خاک ایران
دوره 50، شماره 5
مهر 1398
صفحه 1169-1181

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