تاثیر اصلاح فرم هندسی پله‌های سرریز پلکانی بر پارامتر‌های هیدرولیکی و استهلاک انرژی جریان

نوع مقاله : مقاله پژوهشی

نویسندگان

گروه عمران، دانشکده عمران و نقشه برداری، دانشگاه زنجان، زنجان، ایران

10.22059/ijswr.2022.342428.669257

چکیده

سرریزهای پلکانی یکی از سازه­های متداول به­منظور استهلاک انرژی بوده که از طریق پله­ها با ایجاد آشفتگی و مقاومت اصطکاکی بیشتر در برابر جریان، استهلاک انرژی در طول سازه را افزایش می­دهد. در این تحقیق، با انجام یکسری آزمایشات، تاثیر اصلاح فرم پله­ها با اعمال همزمان المان­هایی بر روی پله و لبه آن بر روی الگوی جریان، نقطه شروع هوادهی بر روی سرریز، مشخصات پرش هیدرولیکی در پایین­دست و میزان استهلاک انرژی جریان عبوری از مدل­های سرریز مورد ارزیابی قرار گرفت. المان­های لبه بصورت ممتد و برش خورده و المان­های روی پله در آرایش­های مختلف روی پله قرار گرفتند و نتایج با حالت سرریز پلکانی ساده مقایسه شدند. در نهایت با اعمال این المان­ها بر روی یکی از سرریز­های مورد بهره­برداری شده، تاثیر اصلاح پله­ها بر مشخصه جریان ارزیابی گردید. نتایج نشان داد که بکارگیری همزمان المان­های روی پله و لبه باعث برخی تلاطم و نوسانات بر روی سطح جریان شده اما بر روی رژیم جریان تاثیر چندانی ندارد. اختلاط جریان پس از برخورد با موانع بر روی نقطه شروع هوادهی تاثیر می­گذارد و باعث انتقال محل نقطه شروع هوادهی به بالادست سرریز پلکانی می­شود. اصلاح پله­ها باعث کاهش عمق ثانویه و طول پرش به ترتیب 29/26 و 24/34 درصد و افزایش 38/14 درصدی در میزان اصلاح انرژی جریان می­گردد. تأثیر المان­های الحاقی در عملکرد مدل­­های اصلاحی در دبی­های پایین بیشتر است. اصلاح پله­های سرریز پلکانی سیاه­بیشه بالا با الحاق المان­­ها بر روی پله و لبه آن باعث کاهش 8/9 درصدی سرعت جریان در پایین­دست سرریز، افزایش 63 درصدی انرژی آشفته و افزایش 32/11 درصدی در میزان استهلاک انرژی جریان می­گردد.

کلیدواژه‌ها


عنوان مقاله [English]

The Effects of Modifying the Geometric Shapes of steps in Stepped Spillway on Hydraulic Parameters and Energy Dissipation

نویسندگان [English]

  • Amir Ghaderi
  • Saeed Abbasi
Department of Civil Engineering, Faculty of Engineering, University of Zanjan, Zanjan 537138791, Iran
چکیده [English]

Stepped spillways are a common structure for energy dissipation since they create turbulence and frictional resistance to flow through the steps, which increases energy dissipation along the structure. In this study, by performing a series of tests, the effect of modifying the shape of steps by simultaneously applying elements on the steps and their edge on the flow pattern, inception point on the spillway, hydraulic jump characteristics in the downstream, and energy dissipation were investigated. The pool edge elements were of two types (height and notch), and the elements placed on the steps were different arrangements. Their results were compared to the flat stepped spillway. Finally, by applying these elements on an operational spillway, the effect of step modifications on the flow characteristic was evaluated. The results showed that the simultaneous application of elements on the steps and the edge caused some turbulence and instabilities on the flow surface with fluctuations and had little effect on the flow regime. Turbulence flow due to colliding with elements affects the inception point, causing it to be transferred upstream of the stepped spillway. Step modification reduces the sequent depth and jump length by 26.29 and 34.24%, respectively, and increases the energy dissipation rate by 14.38%. The effect of additional elements on the performance of the stepped spillway is high at low discharges. Modification of Siah-Bisheh stepped spillway by applying elements on the steps reduces the flow velocity by 9.8% downstream of the spillway, increases turbulent kinetic energy (TKE) by 63%, and enhances the energy dissipation rate by 11.32%.

کلیدواژه‌ها [English]

  • Modified stepped spillway
  • Step elements
  • Energy dissipation
  • Hydraulic jump characteristics
  • Siah-Bisheh stepped spillway
Akhgar, S., Roushangar, K. (2020). Numerical and experimental study of pitched steps effects in stepped spillway on the hydraulic parameters and energy dissipation in the skimming flow. Amirkabir Journal of Civil Engineering, 52(8), 2043-2058. (In Farsi)
Carosi, G. and Chanson. H. 2008. Turbulence characteristics in skimming flows on stepped spillways, Canadian Journal of Civil Engineering. 35 (9): 865–880.
Chanson, H. and Toombes, L. (2001). Air–water flow down stepped chute: turbulence and end flow structune observations, Internationadl Journal of multiphase Flow. 28.
Daneshfaraz, R. Bagherzadeh, M. Ghaderi, A. Di Francesco, S. and Asl, M. M. (2021a). Experimental investigation of gabion inclined drops as a sustainable solution for hydraulic energy loss. Ain Shams Engineering Journal, 12(4), 3451-3459.
Daneshfaraz, R., Aminvash, E., Ghaderi, A., Kuriqi, A., & Abraham, J. (2021b). Three-dimensional investigation of hydraulic properties of vertical drop in the presence of step and grid dissipators. Symmetry, 13(5), 895.
Felder S. Guenther P. and Chanson. H. 2012. Air-Water Flow Properties and Energy Dissipation on Stepped Spillways: a Physical Study of Several Pooled Stepped Configurations. Hydraulic Model Report No. CH87/12, School of Civil Engineering, The University of Queensland, Brisbane, Australia.
Felder. S. and Chanson. H. (2014). Effects of step pool porosity upon flow aeration and energy dissipation on pooled stepped spillways. Journal of Hydraulic Engineering. 140 (4): 04014002
Felder. S. Geuzaine. M. Dewals. B. and Erpicum. S. (2019). Nappe flows on a stepped chute with prototype-scale steps height: Observations of flow patterns, air-water flow properties, energy dissipation and dissolved oxygen. Journal of Hydro-environment Research. 27: 1-19.
Ghaderi, A. Abbasi, S. Abraham, J. and Azamathulla, H.M. (2020). Efficiency of trapezoidal labyrinth shaped stepped spillways. Flow Measurement and Instrumentation, 72, 101711.
Ghaderi, A.; Abbasi, S. and Di Francesco, S. )2021 (. Numerical Study on the Hydraulic Properties of Flow over Different Pooled Stepped Spillways. Water, 13, 710.
Ghaderi. A. and Abbasi. S. (2021a). Experimental and Numerical Study of the Effects of Geometric Appendance Elements on Energy Dissipation over Stepped Spillway. Water, 13, 957.
Ghaderi, A., and Abbasi, S. (2021b). Experimental Study of Energy Dissipation over Stepped Spillway with Appendance Elements on the Steps. Iranian Journal of Irrigation & Drainage, 15(3), 494-509. (In Farsi)
Gonzalez, C.A. and Chanson, H. (2004). Scale Effects in Moderate Slope Stepped Spillways Experimental Studies in Air-Water Flows, 8th National Conference on Hydraulics in Water Engineering, Australia. 560.
Hamedi. A. Mansoori. A. Malekmohamadi. I. and Roshanaei. H. (2011). Estimating energy dissipation in stepped spillways with reverse inclined steps and end sill. World Environmental and Water Resources Congress. Bearing Knowl Sustain. ASCE.
Heydari orojlo, S., Mousavi Jahromi, S., Adib, A. (2010). Influence of the steeped spillway slope on the number of optimal steps. Irrigation Sciences and Engineering, 33(2), 127-140. (In Farsi)
Jam, M., Talebbeydokhti, N., and Mardashti, A. (2014). Evaluation of Energy Dissipation over Dentate Blocks Spillway and Comparing the Energy Dissipation with Stepped Spillway. Journal of Hydraulics, 9(2), 1-10. (In Farsi)
Mero. S. and Mitchell. S. (2017). Investigation of energy dissipation and flow regime over various forms of stepped spillways. Water and Environment Journal, 31 (1): 127-137.
Morovati, K. Eghbalzadeh, A. and Soori, S. (2016). Study of Energy Dissipation of Pooled Stepped Spillways. Civil Engineering Journal. 2(5), 208-220.
Nohani. E. bahadoribirgani. B. Jalili. D. and Mirazizi. S. (2015). Study The Effect of The Number of steps on Energy Dissipation of Stepped Spillways in Non-Nappe or Skimming Flow. Journal of Novel Applied Sciences. 4 (9): 932-939.
Rajaratnam, N. (1990). Skimming Flow in Stepped Spillways. Journal of Hydraulic Engineering. 116: 587–591.
Rice, C.E. and Kadavy, K.C. (1996). Model study of roller compacted concrete stepped spillway. Journal of Hydraulic Engineering. ASC., 122(6): 292-297.
Roushangar, K., and Akhgar, S. (2019). Numerical and experimental Study of the influence of Wedge Elements on Roughness and Energy dissipation over stepped spillway. Iranian Journal of Irrigation & Drainage, 13(1), 78-88. (In Farsi)
Shahheydari, H. Nodoshan, E. J. Barati, R., and Moghadam, M. A. (2015). Discharge coefficient and
energy dissipation over stepped spillway under skimming flow regime. KSCE Journal of Civil Engineering. 19(4), 1174-1182.
Sohrabi, Z., Sarvarian, J., and Mamizadeh, J. (2020). Development a Two-objective Simulation - Optimization Model for Optimal Design of Geometric Dimensions and Slope of the Stepped Spillway of Upstream Siah-Bisheh Dam Using NSGA-II Algorithm. Iranian Journal of Soil and Water Research, 51(2), 469-478. (In Farsi)
Sarkamaryan, S. and Ahadiyan, J. (2020). Mathematical modeling of energy loss on Stepped Spillway Using ANSYS-CFX Numerical Model. Irrigation Sciences and Engineering, 43(1), 43-56. (In Farsi)
Torkaman Sarabi, M., Rajaei, S., Gol Kar.Hamzehe Yazd, H. (2020). The Effect of Stone Aggregate Size on Energy loss in Gabion Stepped Spillway. Iranian Journal of Irrigation & Drainage, 14(4), 1175-1186. (In Farsi)
Tokyay, N. D. (2005). Effect of channel bed corrugations on hydraulic jumps. Global Climate Change Conference, EWRI, May 15-19, Anchorage, Alaska, USA, 408(173), 408-416.
Water Research Institute. (2005). Final report of the hydraulic model of the upper and lower Siah Bisheh dam reserves. Department of Hydraulic Structures, Water Institute, Ministry of Energy, First volume, Iran.