نشریه مهندسی عمران امیرکبیر

نشریه مهندسی عمران امیرکبیر

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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