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استهلاک انرژی در سرریزهای کلیدپیانویی مستطیلی و ذوزنقه ای | ||
| تحقیقات مهندسی سازه های آبیاری و زهکشی | ||
| دوره 24، شماره 90، خرداد 1402، صفحه 17-32 اصل مقاله (923.71 K) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/idser.2023.362286.1545 | ||
| نویسندگان | ||
| حسین سهراب زاده انزانی* 1؛ مسعود قدسیان2 | ||
| 1دانشجوی سابق کارشناسی ارشد، مهندسی آب و سازههای هیدرولیکی، دانشگاه تربیت مدرس-تهران | ||
| 2استاد هیدرولیک، دانشکده مهندسی عمران و محیط زیست، دانشگاه تربیت مدرس- تهران | ||
| چکیده | ||
| سرریزهای کلیدپیانویی از جدیدترین سرریزهای غیرخطی هستند که نسبت به سرریزهای لبه تیزخطی طول تاج بیشتری دارند و برای تنظیم و کنترل جریانِ رودخانهها، کانال ها و سدها بهکار گرفته می شوند. برای بهبود ضریب آبگذری سرریزهای کلید پیانویی مطالعات فراوانی شده است، اما مقایسه ای بین استهلاک انرژی سرریزهای کلیدپیانویی مستطیلی و ذوزنقه ای صورت نپذیرفته است. در مطالعۀ پیش رو به بررسی و مقایسۀ استهلاک انرژی و ضریب آبگذری سرریزهای کلیدپیانویی مستطیلی و ذوزنقه ای پرداخته میشود. آزمایش ها در آزمایشگاه هیدرولیک دانشگاه تربیت مدرس و در فلومی به ارتفاع ۰/۹، عرض ۰/۷۵ و طول 10 متر انجام پذیرفته است. مطابق مشاهدات آزمایشگاهی، در سرریز کلیدپیانویی مستطیلی و ذوزنقه ای برخی تفاوتها در میدان جریان مشاهده میشود. در هدهای خیلی کم هوادهی در هیچ یک از سرریزها مشاهده نشده و پرش هیدرولیکی نیز در انتهای کلیدهای خروجی سرریز رخ نداده است، اما با افزایش هد، پرش هیدرولیکی در انتهای کلیدهای سرریز تشکیل میگردد که در دبیهای بالاتر اثری از آن یافت نمی شود.؛ همچنین مشخص گردید سرریز کلیدپیانویی ذوزنقهای در استهلاک انرژی عملکرد بهتری دارد تا سرریز مستطیلی، به طوری که عملکرد آن حدود ۳ درصد بیشتر از عملکرد سرریز کلیدپیانویی مستطیلی است. افزونبراین، متوسط ضریب آبگذری سرریز کلیدپیانویی ذوزنقه ای، در مقایسه با سرریز کلیدپیانویی مستطیلی، ۱۱ درصد بیشتر است. | ||
| کلیدواژهها | ||
| استهلاک انرژی؛ سیلاب؛ سرریز کلیدپیانویی؛ ضریب آبگذری | ||
| عنوان مقاله [English] | ||
| Energy Dissipation of Rectangular and Trapezoidal Piano Key Weir | ||
| نویسندگان [English] | ||
| Hossein Sohrabzadeh-Anzani1؛ Masoud Ghodsian2 | ||
| 1Former master's student, water and hydraulic engineering, Tarbiat Modares University-Tehran | ||
| 2Professor of Hydraulics, Faculty of Civil and Environmental Engineering, Tarbiat Modares University, Tehran | ||
| چکیده [English] | ||
| Extended Abstract Introduction Piano key weirs (PKWs) are a kind of non-linear weirs, initially introduced by Hydrocoop in France (Blanc and Lempérière, 2001). PKWs include the inlet and outlet keys as well as the inclined bottom. Due to their high compatibility with the site and their economic and hydraulic performance, PKWs have been used in different countries including North America, Europe, Asia, and Australia (e.g., Malarce Dam, France, Lake Peachtree Dam, GA, USA, Dakmi 2 and Van Phong Barrage, Vietnam). There is a wide range of studies addressing the discharge coefficient of PKWs, but the energy dissipation of rectangular and trapezoidal PKWs has not been compared so far. Hence, in this paper the energy dissipation of these weirs are evaluated and compared. Methodology Tests were conducted in the hydraulic laboratory of Tarbiat Modares University, Tehran to assess the energy dissipation and flow properties downstream of rectangular and trapezoidal PKWs. Tests were performed using a flume with 10 m length, 0.75 m width, and 0.9 m height (Fig. 1). The water was provided by an underground sump. PK weir was installed and sealed at 4 m away from the flume inlet, so the minimum flow turbulence was achieved. The discharge was adjusted by changing the speed of the pumps using a control panel. The upstream and downstream flow depths were measured at (Crookston, 2010) and (Eslinger and Crookston, 2010) away from the weir upstream and downstream, respectively, using digital point gage with an accuracy of ±0.1 mm. The weir specifications are listed in Table 1. Experiments were conducted for various discharges and approach flow depths. Results The flow field upstream of PKWs was almost uniform and no turbulence was observed on the water surface. The flow deviated near the PKW with streamlines along the inlet and outlet keys and over the weir walls. Flow deviation led to an increased unit discharge in the outlet keys. Meanwhile, the local velocity was increased, leading to a positive acceleration. The observations showed that this was accompanied by water level decline, and increased downstream turbulence. The flow jet passing over the crest was accompanied by the interaction of three colliding jets. This interaction was the result of the collision between the flow nappies from lateral crests and the approach flow in the outlet keys (Fig. 4). The resulting interactions led to significant turbulence, and expansion of flow at the downstream. As the head increased, the outlet key discharge was increased, and energy dissipation was decreased. Figure 5 shows variations of the energy dissipation for rectangular and trapezoidal PKWs. The relative energy dissipation by trapezoidal PKW was more than that of rectangular PKW, by average of abbot 3%. Figure 6 shows the residual energy of the PKW versus discharge for rectangular and trapezoidal PKWs. It is clear that as the discharge increased, increased. Furthermore, the ascending rate of was higher for lower discharges. This is due to the local submersion upstream of the weir at higher discharge. Conclusion Despite the length of the used crest of trapezoidal PKW being less than rectangular PKW, energy dissipation of trapezoidal PKW is higher than that of rectangular PKW. The average discharge coefficient for trapezoidal PKWs is higher than that for rectangular PKW. The flow characteristics is different for rectangular and trapezoidal PKWs. For , no aeration is occurred. For , a week hydraulic jump is formed at the end of the weir outlet keys. New equation was obtained for estimation of energy dissipation. | ||
| کلیدواژهها [English] | ||
| Energy Dissipation, Flood, Piano Key Weir, Discharge Coefficient | ||
| مراجع | ||
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