بررسی آزمایشگاهی استهلاک انرژی در شیب‌شکن‌های قائم مجهز به صفحات مشبک افقی با جریان فوق بحرانی

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشیار، گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران.

2 استادیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران

3 دانشجوی کارشناسی ارشد، گروه مهندسی عمران، دانشگاه مراغه، مراغه، ایران

چکیده

در این مطالعه با هدف افزایش استهلاک انرژی در شیب­شکن­های قائم با جریان فوق بحرانی در بالادست، از صفحات مشبک به صورت افقی در لبه شیب­شکن­ قائم به عنوان مستهلک­کننده انرژی اضافی جریان استفاده گردید. آزمایش­ها برای یک شیب­شکن قائم ساده و شیب­شکن مجهز به صفحات مشبک با دو نسبت تخلخل و سه بازشدگی دریچه تنظیم گردید. در طی آزمایش­ها مشاهده شد که صفحه مشبک افقی بعد از شیب­شکن، با تقسیم جت در حال سقوط به تعداد بسیار زیادی از جت­های کوچک عمودی باعث افزایش تداخل هوا و تلاطم در داخل استخر گردید. مقایسه نتایج نشان داد که استفاده از این صفحات در شیب­شکن­های قائم باعث افزایش عمق نسبی پایین­دست، عمق نسبی استخر و استهلاک انرژی نسبی نسبت به شیب­شکن قائم ساده می­گردد. همچنین با بررسی نتایج مشخص گردید که با افزایش عدد فرود بالادست و کاهش عمق بحرانی نسبی، استهلاک انرژی نسبی افزایش می­یابد. این درحالی است که تخلخل صفحات مشبک تأثیری بر روی این پارامتر ندارد. بررسی و مقایسه نتایج مربوط به شیب­شکن­های قائم ساده و مجهز به صفحه مشبک نشان داد که استفاده از صفحات مشبک افقی در این سازه­ها باعث کاهش طول حوضچه آرامش و حذف سازه حوضچه آرامش می­گردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Experimental Investigation of Energy Dissipation in Vertical Drops Equipped with a Horizontal Screen under Supercritical Flow

نویسندگان [English]

  • Rasoul Daneshfaraz 1
  • Sına Sadeghfam 2
  • vadoud Hasanniya 3
1 Associate Professor, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.
2 Assistant Professor, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.
3 M.Sc. Student, Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Maragheh, Iran.
چکیده [English]

In this study, horizontal screens were used in the edge of vertical drops, as an excessive energy dissipater of flow, to increase dissipation of energy in vertical drops with the supercritical flow at upstream. Experiments adjusted for a simple vertical drop and a drop equipped by screens with two porosity values and three openings of the upstream sluice gate. During the experiments, it was observed that the horizontal screen after drop increased the air entrance and turbulence in the pool due to dividing the falling jet into a large number of small vertical jets. The results indicate that using these plates in the vertical drops increases the relative depth of downstream, relative depth of pool and relative energy dissipation as compared to a simple vertical drop. Also, results showed by increasing the upstream Froude number and decreasing the relative critical depth, the relative energy dissipation increases. However, the porosity of screens has not a significant effect on energy dissipation. Investigation and comparison of the results corresponded to the simple vertical drops and the ones equipped with screens indicated that incorporating the horizontal screens in these structures eliminate or decrease the length of stilling ponds.

کلیدواژه‌ها [English]

  • vertical drop
  • dissipator
  • Froude number
  • downstream depth
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