بررسی عددی اثر تغییر منحنی استاندارد سرریزهای سه‌جانبی در بهبود عملکرد هیدرولیکی آن‌ها

سرریزهای سه‌جانبی از جمله مجراهای تخلیه کننده سدها بوده که علیرغم محدودیت‌های هیدرولیکی، در شرایط خاص توپوگرافی به عنوان بهترین انتخاب مطرح می‌شوند. سرریزهای سه‌جانبی دارای برخی شرایط هیدرولیکی نامناسب هستند که به‌عنوان نمونه می‌توان به تلاطم و آشفتگی جریان، اتلاف انرژی و نیز وارد آمدن ضربات نوسانی شدید آب بر تمامی وجوه سرریز اشاره کرد. در تحقیق حاضر شبیه‌سازی عددی میدان جریان سه‌بعدی پیرامون سرریز جانبی u شکل و آبپایه واقع در انتهای کانال جانبی با استفاده از نرم افزار flow3d مورد توجه قرار گرفته است. در ادامه با پله‌ای نمودن منحنی استاندارد سرریز اوجی سه جانبی، میزان تغییر در عمق جریان و نوسانات فشار دینامیکی در کانال جانبی مورد ارزیابی قرار گرفته است. برای بررسی کمی نوسانات فشار دینامیکی از عدد بدون بعد پارامتر آشفتگی استفاده شده است. نتایج نشان می‌دهد پلکانی نمودن منحنی استاندارد این نوع سرریز موجب کاهش برخورد سفره‌های ریزشی جریان و افزایش عمق جریان در کانال جانبی می‌گردد. از سویی دیگر تغییر منحنی استاندارد، کاهش قابل توجه شدت نوسانات فشار در داخل کانال جانبی را به دنبال دارد.

Numerical Investigating the Effect of Changing the Ogee Profile of Three-Sided Spillways on Improving their Hydraulic Performance

Threesided spillways are one of the important damchr('39')s outlet works that despite their hydraulic limitations, selected as the best option in storage dam under special topographical conditions. Considerable energy losses, the flow high turbulences, and applying great fluctuations shock on walls and bed of the side channel are the hydraulic conditions that must carefully considered in these spillways. In this study, the threedimensional flow filed of Ushaped spillway and endsill of the side channel are simulated using Flow3D and the effect of flow turbulences have been modelled by RNG closure. Comparison of the numerical and experimental results revealed that this model with RNG closure has capable to carefully simulate the turbulence flow field on these structures. The effect of making stepped the ogee profile of the threesided spillway on flow depth and dynamic pressure fluctuations has been numerically evaluated; the nondimensional turbulence index has been used to investigate the fluctuations of the dynamic pressure. The results revealed making stepped the ogee profile causes to reduce the encounter of the side overfalls, and to increase the flow depth in the side channel, in which this lead to considerable decrease in pressure fluctuation intensity. Threesided spillways are one of the important damchr('39')s outlet works that despite their hydraulic limitations, selected as the best option in storage dam under special topographical conditions. Considerable energy losses, the flow high turbulences, and applying great fluctuations shock on walls and bed of the side channel are the hydraulic conditions that must carefully considered in these spillways. In this study, the threedimensional flow filed of Ushaped spillway and endsill of the side channel are simulated using Flow3D and the effect of flow turbulences have been modelled by RNG closure. Comparison of the numerical and experimental results revealed that this model with RNG closure has capable to carefully simulate the turbulence flow field on these structures. The effect of making stepped the ogee profile of the threesided spillway on flow depth and dynamic pressure fluctuations has been numerically evaluated; the nondimensional turbulence index has been used to investigate the fluctuations of the dynamic pressure. The results revealed making stepped the ogee profile causes to reduce the encounter of the side overfalls, and to increase the flow depth in the side channel, in which this lead to considerable decrease in pressure fluctuation intensity. Threesided spillways are one of the important damchr('39')s outlet works that despite their hydraulic limitations, selected as the best option in storage dam under special topographical conditions. Considerable energy losses, the flow high turbulences, and applying great fluctuations shock on walls and bed of the side channel are the hydraulic conditions that must carefully considered in these spillways. In this study, the threedimensional flow filed of Ushaped spillway and endsill of the side channel are simulated using Flow3D and the effect of flow turbulences have been modelled by RNG closure. Comparison of the numerical and experimental results revealed that this model with RNG closure has capable to carefully simulate the turbulence flow field on these structures. The effect of making stepped the ogee profile of the threesided spillway on flow depth and dynamic pressure fluctuations has been numerically evaluated; the nondimensional turbulence index has been used to investigate the fluctuations of the dynamic pressure. The results revealed making stepped the ogee profile causes to reduce the encounter of the side overfalls, and to increase the flow depth in the side channel, in which this lead to considerable decrease in pressure fluctuation intensity.