مطالعه آزمایشگاهی اثر زبری جداره بر مقاومت جریان در کانال‌های مستطیلی روباز

نویسندگان

1 گروه مهندسی عمران، واحد اراک، دانشگاه آزاد اسلامی اراک، ایران.

2 دانشیار مهندسی عمران، گروه مهندسی عمران، دانشکده فنی دانشگاه ارومیه، ارومیه، ایران.

3 دانشگاه آزاد اسلامی واحد اراک، گروه مهندسی عمران، اراک، ایران

4 گروه مهندسی مکانیک، گروه عمران، واحد اراک، دانشگاه آزاد اسلامی اراک، ایران.

چکیده

تعیین رفتار جریان در کانال‌های روباز به منظور طراحی دقیق آنها برای انتقال آب همواره مد نظر محققان هیدرولیک بوده است. روابط قدیمی مانینگ-استریکلر، کولگان و کولبروک-وایت تخمین های غیر دقیقی برای ضرایب مقاومت جریان در کانال‌های زبر مستطیلی ارائه می دهند. در این تحقیق با بکارگیری مدل های آزمایشگاهی، مقاومت جریان در کانال‌های مستطیلی با جداره های صاف و زبر و استفاده از سه نوع مصالح رودخانه ای مورد پژوهش قرار گرفته است. نتایج حاصل نشان می‌دهند که رابطه تصحیح شده استریکلر با میانگین خطای نسبی 56/2‌% قادر به تخمین ضریب زبری nمانینگ می باشد و روابط بازبینی شده کولگان برای کانال‌های صاف و کولبروک-وایت برای کانال‌های زبر با داده‌های آزمایشگاهی مطابقت خوبی با خطای کمتر از 91/4% و ضریب همبستگی 983/0 بدست می دهند. در ادامه، روابط تجربی دیگری نیز برای تخمین ضخامت زبری نیکورادزه،ks  بر حسب اندازه قطر ذرات زبر جداره ارائه شده است. با استفاده از الگوی برنامه نویسی بیان ژن (GEP) رابطه صریح‌ جدیدی برای تعیین ضریب اصطکاک، f، در کانال‌های مستطیلی با زبری یکنواخت با میانگین خطای نسبی 1/5‌% و ضریب همبستگی 981/0 ارائه شده است.

کلیدواژه‌ها


عنوان مقاله [English]

An Experimental Study of the Effect of Boundary Roughness in Rectangular Open Channels

نویسندگان [English]

  • S Javid 1
  • M Mohammadi 2
  • M Najarchi 3
  • MM NajafiZadeh 4
1 Department of Civil Engineering, Islamic Azad University, Arak Branch, Arak, Iran.
2 Associate Prof. in Civil Eng., Dept. of Civil Eng. Faculty of Eng., Urmia University, Urmia, Iran.
3 Department of Civil Engineering, Islamic Azad University, Arak Branch, Arak, Iran
4 Department of Mechanical Engineering, Islamic Azad University, Arak Branch, Arak, Iran.
چکیده [English]

In order to precise design, the determination of flow behavior in open channels have always been subjected by the hydraulic researchers. The traditional Manning-Strickler, Keulegan, and Colebrook-White equations provide inaccurate estimations for resistance coefficients in roughened rectangular channels. In this research, flow resistance coefficients both in smooth and rough rectangular channel sections were investigated by using experimental models and three types of river materials. The results show that the revised Strickler formula estimates Manning's n with an average error about 2.56%; and the revised Keulegan equation for smooth and Colebrook-White equation for roughened channels give some good agreements with the experimental measurements by an error of less than 4.91% and a correlation coefficient of 0.983. Some empirical derived equations are also presented which gives the value of Nikuradse sand equivalent roughness, ks, as a function of roughness diameter size. A new explicit formula presented for friction factor, f, using gene expression programming (GEP) for uniformly roughened rectangular channels with an average relative error 5.1% and the corresponding correlation coefficient, 0.981.

کلیدواژه‌ها [English]

  • Gene Expression
  • Flow Resistance
  • Friction Factor
  • Manning’s Roughness Coefficient
  • Rectangular Channel
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