Abstract




 
   

IJE TRANSACTIONS C: Aspects Vol. 31, No. 12 (December 2018) 2022-2027   

PDF URL: http://www.ije.ir/Vol31/No12/C/5-2968.pdf  
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  EFFECT OF OPENING HOLES ON THE HYDRAULIC PERFORMANCE FOR CRUMP WEIR
 
H. AL-Naely, Z. Al-Khafaji and S. Khassaf
 
( Received: September 08, 2018 – Accepted in Revised Form: October 26, 2018 )
 
 

Abstract    Nowadays, developed and applied hydrology become very important thing in the life due to the wide verity advantages for the applications of this field. Hydraulic Structures such as crump weir are placed in channels to estimate or measure flow rate and flow control devices. In this study there is a new performance for crump weir which appears by adding opening holes in the model of crump weir. Opening holes are working as an energy dissipater and as an improver for the discharge coefficient (Cd). Where the discharge coefficient (Cd) is improved and recorded a higher values in comparison with conventional weir under the same laboratory conditions. The twenty-eight laboratory experiments were carried out using free flow in a horizontal channel of 12 m length, 0.5 m width and 0.35 m depth for a wide range of discharge. The experimental results indicated that Cd values increase by increasing the number opening holes in body of crumb weir. Thus; increasing the holes numbers from one to two and three holes) increase Cd value about (10, 11 and 13%), respectively as compared with traditional weirs without opening holes. On the other hand, The results revealed better flow behaviour for two holes model than one and three holes, the flow is more stable and the transition flow regime has less instabilities and Energy dissipation rate is the maximum. Thus; the weir crumb with three voids are not stable and it was not easy to localized it in the channel.

 

Keywords    Crump Weir; Discharge Coefficient; Energy Dissipation; Hydraulic Jump; Hydraulic Structure; Open Channels

 

چکیده   

امروزه، توسعه و بکارگیری زمینه‌های هیدرولوژی، به دلیل مزیت‌های گسترده‌ای برای کاربرد این حوزه، از اهمیت بسیاری برخوردار است. سازه‌های هیدرولیکی از قبیل کراس پله در کانال‌ها برای تخمین یا اندازه‌گیری جریان و دستگاه‌های کنترل جریان قرار می‌گیرند. در این مطالعه یک عملکرد جدید برای پله‌ی فرو ریختگی وجود دارد که با افزودن سوراخ‌های باز در مدل نفوذ کریستالی ظاهر می‌شود. سوراخ‌های باز شدن به عنوان یک قطره دهنده انرژی و به عنوان یک بهبود برای ضریب تخلیه (Cd) کار می‌کنند؛ از آنجا که ضریب تخلیه (Cd) بهبود یافته است و مقادیر بالاتری را نسبت به معادله متعارف در شرایط آزمایشگاهی مشابه ثبت می‌کند. بیست و هشت آزمایش آزمایشگاهی با استفاده از جریان آزاد در کانال افقی 12 متر طول، عرض 5/0 متر و عمق 35/0 متر برای طیف گسترده‌ای از تخلیه انجام شد. نتایج تجربی نشان داد که مقدار Cd با افزایش تعداد سوراخ‌های باز شدن در بدن موج میانی افزایش می‌یابد. بدین ترتیب؛ تعداد سوراخ‌ها از یک سوراخ به دو سوراخ و سه سوراخ به ترتیب در مقادیر Cd 10%، 11% و 13%، در مقایسه با معابر سنتی بدون باز کردن حفره‌ها، افزایش می‌یابد. از سوی دیگر، نتایج نشان داد که رفتار جریان بهتر برای مدل دو سوراخ از یک و سه سوراخ، جریان پایدارتر است و رژیم جریان‌گذار دارای بی‌ثباتی کمتر است و میزان تلفات انرژی حداکثر است. در نتیجه، شکاف باریک با سه حفره پایدار نیست و برای محلی‌سازی در کانال آسان نیست.

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