ابعاد حفرۀ آبشستگی پایین دست حوضچۀ آرامش از نوع پرش هیدرولیکی با بستر پوشیده از المان‌های شش‌پایه

نوع مقاله: مقاله پژوهشی

نویسندگان

دانشگاه شهید چمران اهواز

چکیده

در این مقاله، توپوگرافی بستر آبرفتی پایین­دست حوضچۀ جدید (بستر پوشیده با المان‌های شش‌پایه) و نیز تغییرات حداکثر عمق حفره برای شرایط هیدرولیکی متفاوت (اعداد فرود اولیه 5/76 تا 9/13) و سه اندازۀ رسوب مختلف بررسی شده است. طول حوضچه در تمام آزمایش‌ها ثابت و متناسب با حداکثر دبی محاسبه شد. نتایج بررسی ­ها نشان داد که حداکثر عمق آبشستگی، در مقایسه با تحقیقات دیگر محققان که در شرایط با بستر صاف بوده است، به­ طور متوسط 61 درصد کاهش داشته است. افزایش اندازۀ ذرات رسوبی از 0/95 به 2/23 میلی­ متر باعث کاهش حداکثر عمق آبشستگی به­ میزان 56 درصد شده ‌است. در آزمایش ­هایی که طول پرش کمتر از طول حوضچه بود عمق حفره نیز کاهش چشمگیری داشته
به­ طوری­ که در نسبت طول پرش به طول حوضچه برابر 0/405 حداکثر عمق آبشستگی به ­طور متوسط 64 درصد کاهش یافته‌ است. شیب شیروانی­ های بالادست و پایین­ دست حفره نیز در تمام آزمایش‌ها اندازه­ گیری شد که برای دیوارۀ بالادست بین 6 و 24 درجه و برای دیوارۀ پایین­ دست بین 2 و 7 درجه است. همچنین، معادلۀ پروفیل طولی بدون بعد آبشستگی در پایین­ دست حوضچۀ آرامش با بستر زبر استخراج گردید.

کلیدواژه‌ها


عنوان مقاله [English]

Scour Dimensions of the Downstream Hydraulic Jump Stilling Basin with Bed Covered with Six-Legs Elements

نویسندگان [English]

  • parvin chahardahcheriki gholi zadeh
  • mahmood Shafai-Bajestan
chamran university
چکیده [English]

Bed topography downstream of the new hydraulic jump stilling basin (covered with six-legs elements) has been investigated in this study. Variation of maximum scour depth for different hydraulic conditions (Froude number ranged from 5.76 to 9.13) and three different sediment particle sizes was studied. The basin length, which was kept constant at all tests, was measured for maximum flow discharge. At this condition the maximum scour depth was measured which was found to be 61% less than that of maximum scour depth reported by other studies conducted for smooth bed basin. Increase of sediment particles from 0.95 mm to 2.23 can cause the scour depth to reduce by as much as 56%. In those tests which the jump length was less than the basin length, the scour depth was reduced significantly. For test with jump length to basin length ratio equal to 0.405, the scour depth shows reduction of 64% on an average. The upstream and downstream scour banks angles was measured for all tests which was to be equal to 6-24 degrees and 2-7 degrees respectively. The best fitted relation for dimensionless longitude bed profile also was obtained and presented.

کلیدواژه‌ها [English]

  • Basin
  • Hydraulic
  • Scour
  • Six-Legs Element

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