شبیه‌سازی عددی جریان در حوضچه آرامشUSBR II با دیواره‌های همگرا و پله‌های انتهایی

نویسندگان

1 عضو هیات علمی دانشگاه تبریز

2 دانشکده عمران، دانشگاه تبریز

3 دانشگاه سمنان

4 دانشکده عمران، دانشگاه آزاد واحد خرم آباد

چکیده

حوضچه های‎ ‎آرامش‎ ‎از‎ ‎مهمترین‎ ‎سازه‌های‎ ‎مستهلک‎ ‎کننده‎ ‎انرژی‎ ‎می باشند بطوریکه تغییر شکل حوضچه آرامش می-‏تواند باعث عملکرد‎ ‎هیدرولیکی‎ ‎بهتر آنها شود. در این مطالعه، با پلکانی کردن انتهای حوضچه آرامشUSBR II‏ مدل سد ‏نازلوچای و همگرا نمودن دیواره های حوضچه، پارامترهای فشار، پروفیل سطح آب، راندمان پرش هیدرولیکی و ‏استهلاک انرژی جنبشی بررسی شد. برای این منظور در نرم‏‎‌ افزارFlow-3D‎‏ با استفاده از روشVOF‏ و مدل آشفتگیRNG‏ ‏، جریان در حوضچه آرامش همگرا با زوایای همگرایی5، 5/7 ،10 و5/12 درجه برای دبی 830 متر مکعب بر ثانیه ‏شبیه‌سازی گردید. جهت صحت سنجی مدل عددی، از مقادیر آزمایشگاهی فشار استفاده شد. نتایج مدل سازی نشان داد ‏که پلکانی کردن انتهای حوضچه و همگرایی دیواره ها باعث افزایش عمق پایاب و مانع خروج پرش از حوضچه آرامش ‏می گردد. همچنین، همگرا کردن دیواره های حوضچه تأثیر مثبتی بر راندمان دارد. همگرا کردن دیواره ها باعث مستغرق ‏شدن پرش هیدرولیکی می شود، درحالیکه پرش در حوضچه آرامش با دیواره های موازی بصورت آزاد می باشد. ‏بهترین زاویه همگرایی از نظر عملکرد، حوضچه با زاویه همگرایی 5 درجه می باشد که راندمان به میزان 136 درصد ‏نسبت به حوضچه با دیواره های موازی افزایش می یابد. مقایسه نتایج استهلاک انرژی برای مقاطع مختلف حوضچه در ‏اعماق متفاوت نشان داد که حداکثر استهلاک انرژی در اعماقی بین30-20 درصد عمق جریان رخ می‌دهد که در نظر ‏گرفتن این نکته، باعث طراحی سازه ایِ بهتر حوضچه آرامش می شود. ‏

کلیدواژه‌ها


عنوان مقاله [English]

Numerical Simulation of Flow in the USBR II Stilling Basin with Converging Walls and End Steps

نویسندگان [English]

  • Nasim Soori 2
  • Saba soori 3
  • Hamid Reza Baba Ali 4
2 Faculty of civil engineering, University of Tabriz
3 Ph.D. Student, Department of Civil Engineering, Semnan University, Semnan, Iran
4 Faculty of Civil Engineering, Islamic Azad University, Khorramabad Branch, Lorestan, Iran
چکیده [English]

The stilling basins are of the most important energy dissipater structures, and changes in their shape lead to a better ‎hydraulic performance of them. In this study, the impacts of steps at the end of USBR II stilling ‎basin of Nazloo-Chay ‎dam and walls convergence on the pressure, water surface profile, efficiency of ‎hydraulic jump and energy dissipation ‎were investigated. For this purpose, the flow was ‎simulated using the VOF method and RNG turbulent model in ‎the ‎converging stilling basin (with convergence angle of 5◦, 7.5◦, 10◦ and 12.5◦) and discharge rate of 830 m3/s. The ‎numerical model was ‎verified by pressure's experimental data. The results showed that existence end steps and ‎convergence walls led to an increase in tail water depth and prevented hydraulic jump from exhausting out of ‎stilling ‎basin. Also, the convergence walls caused the jump to be submerged contrary to the free jump occurring in ‎stilling basins with parallel walls having free jumps. Convergence Walls had a positive impact on the efficiency of the ‎hydraulic jump. In this study, the converging stilling basin with 5◦ convergence angel gave a great performance, and the ‎efficiency increased by 136% in comparison to stilling basin with parallel walls. The comparison of the ‎results of energy ‎dissipation for different sections of stilling basin at different flow depths ‎demonstrated that the maximum energy ‎dissipation occurred in the depths between 20-30% of flow depth. These results may be considered for improving the ‎stilling basins design.‎

کلیدواژه‌ها [English]

  • Convergent angels
  • Convergence stilling basin
  • Efficiency of hydraulic jump
  • Energy dissipation
  • numerical model
  • Turbulence
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