اثر شکاف بر توپوگرافی بستر حول صفحه‌ مثلثی متصل به ساحل در قوس 90 درجه

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشگاه شهید چمران اهواز

2 دانشگاه شهید چمران اهواز

چکیده

آبشکن‌ها اگرچه توانسته‌اند در حفاظت از قوس رودخانه‌ها عملکرد مناسبی داشته باشند، اما از روند آبشستگی موضعی حول دماغه مصون نیستند. تحقیقات اخیر نشان داده است که صفحات مثلثی متصل به ساحل به‌دلیل شکل هندسی سازه، نسبت به آبشکن‌‌ها آبشستگی کمتری در دماغه ایجاد می‌کنند. ایجاد شکاف در سازه یکی از راه‌کارهای مهندسان در اصلاح الگوی جریان اطراف سازه می‌باشد. به‌منظور دست‌یابی به اهداف تحقیق حاضر شکافی مستطیلی با درصد بازشدگی برابر با 10 درصد سطح مؤثر صفحه و در موقعیت موازی با وتر، در صفحه‌ی مثلثی متصل به ساحل ایجاد شده است. سپس در زوایا و شرایط هیدرولیکی متفاوت (287/0، 304/0 و 322/0) اثر شکاف بر توپوگرافی بستر بررسی شده است. نتایج نشان داد متوسط درصد کاهش بیشینه عمق آبشستگی توسط شکاف ایجاد شده در زوایای 23، 30، 40 و 60 درجه به ترتیب 70‌، 20‌، 17‌و 54‌ درصد بوده است. همچنین شکاف باعث دور کردن چاله‌ی آبشستگی از ساحل بیرونی شده است. با افزایش عدد فرود جریان، بیشینه عمق آبشستگی در صفحات شاهد و شکاف دار، افزایش یافت.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The effect of slot on bed topography around the bank attached triangular vane in 90 degree bend

نویسندگان [English]

  • farshid amirsalari meymani 1
  • ahmad fathi 1
  • mohammad mahmoodian shooshtari 2
1 shahid chamran university of ahvaz
2 Shahid Chamran University of Ahvaz
چکیده [English]

Although the spur dikes have an appropriate performance to protect the rivers’ bank, these structures are not immune against the local scour around their tips. Recent researches have shown that the bank attached triangular vanes have less scour depth at their tips toward the spur dikes because of their geometrical shape. One of the methods to improve the flow pattern around the structures is creating slots in the structure to reduce the maximum scour depth around the structure’s tips. In order to achieve the purposes of the present study, a rectangular slot (with an opening percentage equal to 10 percent of the effective vane surface and the location of the slot being parallel to the chord) has been created in the bank attached triangular vane. Then the effect of the slot on the bed topography was analyzed at different angles and hydraulic conditions (0.287, 0.304 and 0.322). The research results showed that the average reduction of the maximum scour depth by means of a slot at the angles of 23, 30, 40 and 60 degrees have been 70, 20, 17 and 54 percent, respectively. Also, the created slot in the vane caused the maximum scour depth to be formed away from the outer bank. By increasing the Froude number, the maximum scour depth increased at sample-slotted vanes.

کلیدواژه‌ها [English]

  • River bend
  • Bank attached vane
  • Slot
  • Maximum scour depth
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