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بررسی تاثیر تعداد دفلکتورهای مثلثی بر استهلاک انرژی وطول پرتابه در سرریزهای جامی شکل | ||
| تحقیقات مهندسی سازه های آبیاری و زهکشی | ||
| مقاله 8، دوره 21، شماره 78، اردیبهشت 1399، صفحه 117-138 اصل مقاله (1.07 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22092/idser.2019.126593.1394 | ||
| نویسندگان | ||
| فردوس میرسالاری* 1؛ محمود شفاعی بجستان2 | ||
| 1دانشجوی کارشناسی ارشد گروه سازه های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز، اهواز، ایران | ||
| 2استاد گروه سازه های آبی، دانشکده مهندسی علوم آب، دانشگاه شهید چمران اهواز، اهواز، ایران | ||
| چکیده | ||
| در این مطالعه، با توجه به ناچیز بودن تعداد پژوهشها در مورد کاربرد دفلکتور ممتد در سرریز جامی، به عنوان راهکاری جدید، تأثیر دفلکتور غیرممتد مثلثی در پرتابکنندۀ جامی بر میزان استهلاک انرژی و طول پرتابه بهصورت آزمایشگاهی بررسی شد. آزمایشها بر پرتابکننده جامی در چهار دبی و سه عمق پایاب متفاوت برای دو، سه و چهار دفلکتور مثلثی با زاویه برخاست 47 درجه و بدون دفلکتور اجرا شد. در مقایسۀ کلی، عملکرد پرتابکننده با دفلکتور در استهلاک انرژی و طول پرتابه بهتر از پرتابکنندۀ بدون دفلکتور است. بیشترین میزان تلفات انرژی در برابر ، در شرایط تشکیل پرش هیدرولیکی کامل برای چهار دفلکتور در برابر 0.027 معادل 65.87 درصد و کمترین میزان تلفات در برابر ، در شرایط تشکیل پرش مستغرق کامل برای حالت بدون دفلکتور در برابر 0.049 معادل 47.86 درصد است. بیشترین طول پرتابه در برابر ، با تشکیل پرش هیدرولیکی کامل، در برابر 0.049 در پرتابکنندۀ بدون دفلکتور معادل 95.6 سانتیمتر و کمترین میزان طول پرتابه در برابر ، برای چهار دفلکتور در برابر 0.027، با تشکیل پرش هیدرولیکی مستغرق کامل معادل 25.6 سانتیمتر است. بهدلیل افزایش میزان تلفات انرژی (تحت تأثیر اختلاط جتهای عبوری دفلکتورها و پرتابکننده) و کاهش طول پرتابه، پرتابکننده با دفلکتور مثلثی توصیه میشود. | ||
| کلیدواژهها | ||
| پرش اسکی؛ پرش هیدرولیکی؛ تلفات انرژی؛ عمق پایاب | ||
| عنوان مقاله [English] | ||
| Study of Effect of Number of Tri-angular Deflectors on Energy Dissipation and Jet Length at Ski-Jump Spillway | ||
| نویسندگان [English] | ||
| Ferdous Mirsalari1؛ Mahmood Shafai-Bejestan2 | ||
| 1Dept. of Hydraulic structures, Faculty of Water Science and engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. | ||
| 2Dept. of Hydraulic structures, Faculty of Water Science and engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran. | ||
| چکیده [English] | ||
| Introduction In reservoir dams, high kinetic energy at downstream of their spillways can cause destruction of the spillway and its surrounding areas which results significant loss of life and financial loss, so it is necessary to investigate the performance of energy dissipation structures during its operation. In this regard, the effects of the number of deflectors located just donsream of its chute on energy dissipation and its projectile length were investigated experimentally. Deflectors separate the incoming jet to few smaller jets, which pass through the slut between the deflectors or overflow above the deflectors. Therefore, more air mix with the jet flow and the separated jets hit each other, the results of which are increase in the amount of energy dissipation. On the other hand, the existence of deflectors reduces projectile length, makes smaller submerged ponds easier to maintain, and reduces costs. Methodology At the beginning of flume, a ski jump structure, with a height of 100 cm, a length of 90 cm and a radius of 14 cm was made by the galvanized sheet. Adjustment of the alignment and location of the hydraulic jump occurred by a slide gate located at the downstream of the flume. At each stage, the number of deflectors was deployed at the starting point of the jumper launcher such that the bottom side of the deflector was aligned to the horizon and the distance of the first deflector from the wall of the flume was halfway between the deflectors. Experiments were performed at four different ratios of critical depth to the total head (= 0.02, 0.035, 0.03 and 0.049) and three different tailwater depths. In these conditions, the deflector-free jumper launcher was tested using two, three and four deflectors. Relative energy dissipation was calculated by measuring the total energy in the upstream reservoir and downstream of the jetty overflow immediately after the ski jump, and projectile length was determined using projectile shooting and Get Data Graph Digitizer softwar. Results and Discussion Data analysis showed that for both cases, with deflector and without deflector, the relative energy dissipation rate decreased with increasing ratio of (Yc)/H , critical depth to the head, in each of the three adjoining depths. Because with increasing (Yc)/H as the discharge increases, the jet flows more rapidly mix with the air, which is less effective in resisting the jet launcher, mixing air and water. At a constant number of deflectors and at a constant (Yc) /H, the relative energy dissipation rate in the free hydraulic jump is greater than that int semi submerged jump and in the semi submerged jump more than that in full submerged jump, because by decreasing the projectile path, the air contact surface as a resisting agent of motion decreases. Also, at each of the three tailwater water depths, the relative energy dissipation rate increases as the number of deflectors at (Yc)/H increases. This is due to the mixing of jets with each other and the ambient air around the projectiles. In examining the effects of deflectors on the projectile length, the results showed that in both cases, without deflector and with deflector, the projectile length increased with (Yc)/H because with increasing (Yc)/H the flow rate increased, The greater depth of flow on steep slope, the greater slab thickness, the lower slab impact on slip velocity profile, and shear stress as a fluid impedance factor, and hence the more jet flows into the air and larger projectile lengths. At a constant (Yc)/H, the projectile length in the free jump was greater than that of the semi submerged hydraulic jump, and in the semi submerged jump was greater than that in full submerged jump because of increased depth of passage due to submerged hydraulic jump and failure to max. The possible path for the jet outlet from the jumper launcher was to shorten the projectile length. At each of the three steady depths at constant (Yc)/H, as the number of deflectors increased, the projectile length decreased because the path-based deflectors acted as bumpers and decreased the jet launch length and elongation. Conclusions The highest relative energy dissipation in four deflectors at (Yc)/H was 0.027 in free hydraulic jump, 65.87%, and the lowest in two deflectors at (Yc)/H of 0.049 in submerged full hydraulic jump of 6 52 /% and maximum projectile length in two deflectors, (Yc)/H = 0.049 was obtained to be 66.84 cm in free hydraulic jump for the caes of complete submerged was equal to 25.62cm. Based on triangular cross section deflector launcher performance in increasing energy dissipation and decreasing projectile length and saving running and maintenance costs, it is recomended, in terms of hydraulic and economical issues, to use deflector on the ski-jump with structural component. | ||
| کلیدواژهها [English] | ||
| Dams, Hydraulic Jump, Ski-Jump, Tailwater Depth | ||
| مراجع | ||
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Abrishami, J., & Hosseini, S. M. (2003). Open Channel Hydraulics. 11th Edition, Astan Ghods Razavi, Iran. (in Persian)
Ahadian, J., Shahabi, M., & Paypolzadeh, S. (2018). Investigation of the effect of ski-jump geometry on the downstream jet, case study of olia Gotvand dam. 5th National Conference on Irrigation and Drainage Networks Management and Third National Congress on Iran’s Irrigation and Drainage. March 13, Shahid Chamran University, Ahvaz, Iran. (22/12/1396) (in Persian)
Anon, 1987. Design of Small Dams. Third Edition, A Water Resources Technical Publication, Hardcover, United States Department of the Interior Staff. USA.
Barani, Gh. A., & Abbasi-Parvin, E. (2009). Energy Dissipation in Hydraulic Structures. Jahad Daneshgahi of Amirkabir University of Technology. Iran. (in Persian)
Erpicum, S., Archambeau, P., Dewals, B., & Pirotton, M. (2010). Experimental investigation of the effect of flip bucket splitters on plunge pool geometry. Journal of Wasser Wirtschaft, 4, pp. 108-110.
GovindaRao, N. S., & Rajaratnam, N. (1963). The submerged hydraulic jump. Journal of Hydraulic Division, 89(1):139-162
Heller, V., Hager, W. H., & Minor, H. E. (2005). Ski jump hydraulics. Journal of Hydraulic Engineering, 131(5): pp. 347-355.
Khatsuria, R. M. (2005). Hydraulics of Spillways and Energy Dissipaters. Marcel Dekker. New York.
Lenau, C. W., & Cassidy, J. J. (1969). Flow Through spillway flip bucket. Journal of Hydraulic Division, 95(2): 633-648
Mason, P. J. (1993). Practical guidelines for the design of flip buckets and plunge pools. Journal of Water Power and Dam Construction. 45(9/10): pp. 40-45.
Momeni-Vesalian, R., Mousavi-Jahromi, S. H., & Shafai-Bejestan, M. (2006). Scouring caused by rectangular jets at the bottom of ski-jump spillway. The 7th Conference of International River Engineering. Feb. 24-26. Ahvaz, Iran. (in Persian)
Navaei, B. Akhtari, A. A., & Daneshfaraz, R. (2016). Experimental study of flip bucket effect at the end of ogee spillway on energy dissipation and jet length. Water and Soil Science, 25(3): pp. 133-142. (in Persian)
Omidvarinia, M., & Mousavi-Jahromi.S. H. (2013). Effect of continues deflector on jet separation in tri-angular flip bucket (M. Sc. Thesis) Water Science Engineering Faculty, Shahid Chamran University, Ahvaz, Iran. (in Persian)
Peterka, A. J. (1983). Hydraulic design of stilling basins and energy dissipaters. Journal of Engineering Monograph, 25(7): pp. 91-125.
Sadeghi-Askari, M., & Mousavi-Jahromi, S. H. (2012). Experimental investigation on the effect of deflector to angel of flip-bucket on its energy dissipation (M. Sc. Thesis) Water Science Engineering Faculty, Shahid Chamran University, Ahvaz, Iran. (in Persian)
Steiner, R., Heler, V., Hager, W. H., & Minor, H. E. (2008). Deflector ski jump hydraulics. Journal of Hydraulic Engineering. 134(5): pp. 562-571.
Tierney, D. G., & Henderson, F. M. (1963). Flow at the toe of a spillway. Journal of La Houille Blanche. 18(1): pp. 42-50
Tuzandeh-Jani, M. (2011). The effect of flow interference from the body gap on the length of the hydraulic jump at the bottom of the Ogee Spillway (M. Sc. Thesis) Water Science Engineering Faculty, Shahid Chamran University of Ahvaz, Ahvaz, Iran. (in Persian) | ||
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