بررسی آزمایشگاهی آبشستگی ناشی از پرش هیدرولیکی در صفحه مشبک

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه

2 دانشکده فنی-گروه مهندسی عمران-دانشگاه مراغه

3 گروه مهندسی عمران-دانشکده فنی-دانشگاه مراغه

چکیده

در این مطالعه کاربرد صفحه مشبک به‌عنوان مستهلک کننده انرژی جریان آب در پایین­دست سازه­های هیدرولیکی برای کاهش میزان آبشستگی است. برای انجام آزمایش­ها از یک کانال مستطیلی و برای کنترل جریان از یک دریچه کشویی با بازشدگی ثابت استفاده شده است. به­منظور کاهش انرژی جریان خروجی از دریچه کشویی، صفحات مشبک به‌عنوان مستهلک­کننده­های انرژی با منافذ (نسبت روزنه­ای) 40% و 50%، به فاصله 5/1 متری از دریچه قرار گرفته­اند. بعد از صفحه مشبک، بستر متحرک متشکل از ذرات با سه اندازه 8/1 و 6/2 و 2/5 میلی‌متر، به طول 3/1 متر، عرض 3/0 متر و ضخامت 114/0 متر برای مطالعه تأثیر صفحه مشبک روی حداکثر عمق و طول حفره آبشستگی قرار داده­ شد. نتایج مطالعه نشان داد ضخامت و نسبت روزنه صفحه مشبک و فاصله قرارگیری آن از دریچه روی  مقادیر حفره آبشستگی مؤثرند. بیشترین و کمترین عمق و طول حفره آبشستگی به ترتیب در صفحه مشبک با نسبت روزنه 40% و 50% دوبل رخ داد. به ‌طوری که با افزایش نسبت روزنه و ضخامت صفحات، مقادیر حفره آبشستگی کاهش می­یابد. همین طور با افزایش اندازه ذرات میزان آبشستگی نیز روند کاهشی را نشان می­دهد.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Experimental Investigation of the Scouring due to Hydraulic Jump in Screens

نویسندگان [English]

  • Rasoul Daneshfaraz 1
  • Jafar Chabokpour 2
  • Hadi Nezafat 3
1 Department of Civil Engineering, Faculty of Engineering, University of Maragheh,, Iran.
2 Faculty of agriculture, University of Maragheh
3 Department of Civil Engineering, Faculty of Engineering, University of Maragheh,, Iran.
چکیده [English]

In this research, the applicability of the screen sheet, as an energy dissipater at downstream of hydraulic structures, has been studied to reduce the amount of scouring. For operation of the experiments, a rectangular flume with 0.3m in width, 0.45m in height and 5m in length, including a sluice gate for the flow control was used. For reducing energy of outflow from sluice gate, the screen sheets as energy dissipaters with 40% and 50% porosity were placed at distance of 1.5m from the gate. After the screen sheet, the movable beds consist of three different grain sizes of 1.8, 2.6 and 5.2 mm, with the dimensions of 1.3m in length, 0.3m in width and 11.4cm in depth were used to investigate the effect of screen on maximum dimensions of the scouring hole. The results of this study showed that the thickness and porosity of the screen and its distance from the gate are effective parameters on the lenghth and depth of scouring hole. The maximum and minimum depth and length of scouring hole were occurred in the screens with 40% porosity and double 50% porosity, respectively. So that, by increasing the screen’s porosity and thickness, the scouring whole dimension decreases. Also, by increasing the particle dimensions, the scouring hole dimension decreases.

کلیدواژه‌ها [English]

  • Screen
  • Scouring
  • Bed grain sizes
  • Hydraulic jump

مراجع

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تحقیقات آب و خاک ایران
دوره 50، شماره 5
مهر 1398
صفحه 1039-1051

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