بررسی عددی مشخصات هیدرولیکی شیب‌شکن‌‌های قائم با وجود صفحات مشبک و واگرایی تدریجی دیواره

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکترای رشته عمران دانشگاه تبریز

2 داشکده عمران - دانشگاه تبریز، تبریز، ایران

3 دانشیار گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران

چکیده

در تحقیق حاضر، به بررسی مشخصات هیدرولیکی شیب­شکن­های قائم با صفحات مشبک و واگرایی تدریجی دیواره در پایین­دست آن با استفاده از نرم­افزار FLOW- 3D پرداخته شد. برای این منظور از صفحات مشبک با نسبت تخلخل­های 40 و 50 درصد، پنج نسبت واگرایی تدریجی به همراه سه ارتفاع شیب­شکن قائم در محدوده دبی مشخص استفاده گردید. مشخص شد که نتایج عددی با مدل آشفتگی RNG در مقایسه با k-εبه نتایج آزمایشگاهی نزدیک­تر است. همچنین با افزایش ارتفاع شیب­شکن از 15 به 25 سانتی­متر، E/E0Δبه دلیل شدت برخورد جت با کف، افزایش و yP/P  کاهش می­یابد. بیشینهE/E0 Δ­ مربوط به ارتفاع 25 سانتی­متر به میزان 51/60 درصد و کمترین آن برای ارتفاع 15 سانتی­متر به مقدار 44/25 درصد می­باشد. برای یک ارتفاع شیب­شکن ثابت با افزایش دبی،E/E0 Δ­ کاهش و yP/Pافزایش می­یابد. واگرایی دیواره­ موجب تلاطم در کناره­ها و توزیع غیریکنواخت عمق در پایین­دست آن می­شود و ضمن افزایش yP/Pو yd/P باعث افزایش 25 درصدیE/E0 Δ­ می­گردد. وجود صفحات مشبک در پایین­دست شیب­شکن­ باعث افزایش yP/P، yd/Pو همچنین افزایش 44 درصدیE/E0 Δ­ می­گردد. استفاده همزمان از واگرایی دیواره و صفحات مشبک در پایین­دست شیب­شکن­ها باعث افزایش 46 درصدیE/E0 Δ­ و کاهش yP/Pو yd/P می­شود. ثابت شد که سهم مشارکتی استفاده از صفحات مشبک در مقایسه با واگرایی تدریجی دیواره بیشتر است که با بکارگیری همزمان آن­ها،E/E0 Δ­ تا 33/5 درصد افزایش می­یابد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Numerical Investigation of Hydraulic Characteristics of Vertical Drops with Screens and Gradually Wall Expanding

نویسندگان [English]

  • Behnam Nayebzadeh 1
  • Mohammad Ali Lotfollahi-yaghin 2
  • Rasoul Daneshfaraz 3
1 PhD civil student in Tabriz University
2 Professor, ph.d, Faculty of Civil Engineering, University of Tabriz, Tabriz, Iran
3 Department of Civil Engineering, Faculty of Engineering, University of Maragheh, Iran.
چکیده [English]

In the present study, the hydraulic characteristics of vertical drops with screens and the gradual wall expanding downstream using FLOW-3D software are investigated. For this purpose, two porosity ratios of the screens of 40 and 50%, 5 gradually expanding with 3 vertical drop heights in the specified discharge range were used. It was found that the numerical results are closer to the experimental results with the RNG turbulence model than k-ε. By increasing the drop height, the ΔE/E0 due to the jet floor impact intensity increased and yp/P value decreased. The maximum ΔE/E0 for 25 cm height was 51.60% and the lowest for 15 cm was 44.25%. For a constant drop height with increasing discharge, the ΔE/E0 decreased and yp/P increased. The gradually wall expanding causes turbulence on the edges and a non-uniform distribution of yd/P and by increasing yp/P and yd/P, it caused a 25% increase in ΔE/E0. The presence of screens increased yp/P, yd/P, and ΔE/E0 by 44%. The simultaneous use of gradually walls expanding and screens caused a 46% increase in ΔE/E0 and a decrease in yp/P and yd/P values. It was shown that the contribution of screens is greater than the gradually wall expanding, with their simultaneous application increasing ΔE/E0 up to 33.5%.

کلیدواژه‌ها [English]

  • Vertical drop
  • Porosity ratio
  • Turbulence models
  • Gradually wall expanding
  • Flow-3D
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