Numerical Analysis of Energy Dissipation Ratio of Stepped Weirs Designed Using Reverse Stepped Thresholds

Öz

Stepped weirs are a type of weir that has been designed for centuries to dissipate the flow energy on the chute channels. Many studies have been done on step geometry and are still being done to improve these weirs. In this study, the energy dissipation of the weir using reverse step thresholds has been examined with the Flow3D® software. A total of 18 analyzes were conducted using three models and six discharges. According to the results, the stepped weir designed using the reverse step thresholds could dissipate energy up to 18% more than the flat stepped weirs in the skimming flow regime. However, this value decreases as it passes towards the nappe flow regime.

Anahtar Kelimeler

• Stepped spillway
• Flow3D
• Computational fluid dynamics (CFD)

Ters Basamaklı Eşikler Kullanılarak Tasarlanan Basamaklı Savakların Enerji Sönümleme Oranlarının Sayısal Olarak İncelenmesi

Öz

Basamaklı savaklar, şüt kanalı üzerindeki akım enerjisini sönümleyebilmek amacıyla tasarlanan ve yüzyıllardır kullanılan bir savak çeşididir. Bu savakların geliştirilebilmesi amacıyla basamak geometrisi üzerine birçok çalışma yapılmış ve yapılmaya devam etmektedir. Bu çalışma kapsamında, basamak uçlarına eklenen ters basamak geometrisindeki eşiklerin enerji sönümleme oranına etkisi Flow3D® yazılımı ile incelenmiştir. Üç farklı model ve altı farklı debi kullanılarak sürdürülen çalışmada toplam 18 adet analiz yürütülmüştür. Elde edilen sonuçlara göre, her bir basamak ucuna eklenen ters basamaklı eşiklerin, sıçramalı akım şartlarında, klasik basamaklı savaklardan %18’e kadar daha fazla enerji sönümleyebildiği, bu değerin nap akımı rejimine geçildikçe azaldığı gözlenmiştir.

Anahtar Kelimeler

• basamaklı savaklar
• Flow3D
• Hesaplamalı akışkanlar dinamiği (HAD)

Teşekkür

Bu çalışmada kullanılan Flow3D (v11.2) ve Solidworks yazılımları için Fırat Üniversitesi’ne teşekkür ederiz.

Kaynakça

1. Chanson, H. (1998). "Review of Studies on Stepped Channel Flows." Hydraulic Characteristics of Stepped Channel Flows, Workshop on Flow Characteristics around Hydraulic Structures and River Environment, Nihon University, Tokyo, Japan, November, 25 pages.
2. Boes, R.M., (2012). “Guidelines on the design and hydraulic characteristics of stepped spillways”. Commission Internationale Des Grands Barrages, Kyoto, July 2012, Q.94-R.15.
3. Frizell, K.H., and Mefford, B.W. (1991). Designing spillways to prevent cavitation damage. Concrete International, May, pp. 58-64.
4. Felder, S., & Chanson, H. (2016). Simple design criterion for residual energy on embankment dam stepped spillways. Journal of Hydraulic Engineering, 142(4), 04015062.
5. https://en.wikipedia.org/wiki/New_Croton_Dam#/media/File:New_Croton_Dam_NY1.jpg
6. http://dsi.gov.tr/haberler/2017/04/11/141-y%C4%B1ll%C4%B1k-r%C3%BCya-%C3%A7ine-adnan-menderes-baraj%C4%B1
7. http://www.suyapi.com.tr/tr/18852/Cine-Baraji-ve-HES
8. http://www.dsi.gov.tr/kurumsal-yapi/yonetim/genel-mudurumuz/calismalari/2012/06/11/izmir40tesis

9. Özbek, T. (2009). Açık kanal akımlarının hidroliği ve hidrolik yapılar. Teknik Yayınevi.
10. Rice, C. E., & Kadavy, K. C. (1996). Model study of a roller compacted concrete stepped spillway. Journal of Hydraulic Engineering, 122(6), 292-297.
11. Felder, S., Fromm, C., & Chanson, H. (2012). Air entrainment and energy dissipation on a 8.9 slope stepped spillway with flat and pooled steps.
12. Berkün, M., (2007). Su Yapıları Barajlar, Savaklar ve Su Kuvveti Tesisleri. Birsen Yayınevi.
13. Ohtsu, I., and Yasuda, Y. (1997). Characteristics of flow conditions on stepped channels. Proceedings of the 27th IAHR Biennial Congress, San Francisco, Calif., Theme D, pp. 583–588.
14. Chanson, H. (1996). Prediction of the transition nappe/skimming flow on a stepped channel. Journal of Hydraulic Research, 34(3), 421-429.
15. Yasuda, Y., Takahasmı, M., (2000). Characteristics of Skimming Flow over Stepped Spillways. Discussion, Journal of Hydraulic Engineering, 126,11, 869-871.
16. Peyras, L., Royet, P., and Degoutte, G. (1992). Flow and energy dissipation over stepped gabion weirs. ASCE Journal of Hydraulic Engineering, 118(5): 707-717.
17. Chanson, H. (1994). State of the art of the hydraulic design of stepped chute spillways, Hydropower Dams J. 33–42.
18. Chow, V.T. (1959). Open Channel Hydraulics, McGraw-Hill, New York, USA.
19. Essery, I. T. S., & Horner, M. W. (1971). The hydraulic design of stepped spillways. Construction Industry Research and Information Association.
20. Sorensen, R. M. (1985). Stepped spillway hydraulic model investigation. Journal of hydraulic Engineering, 111(12), 1461-1472.
21. Chanson, H. (1993). Stepped spillway flows and air entrainment. Canadian journal of civil engineering, 20(3), 422-435.
22. Chanson, H. (2001). "Hydraulic Design of Stepped Spillways and Downstream Energy Dissipators." Dam Engineering, Vol. 11, No. 4, pp. 205-242.
23. Boes, R. M., & Hager, W. H. (2003). Hydraulic design of stepped spillways. Journal of Hydraulic Engineering, 129(9), 671-679.
24. Wuthrich, D., & Chanson, H. (2015). Aeration performances of a gabion stepped weir with and without capping. Environmental Fluid Mechanics, 15(4), 711-730.
25. Zuhaira, A. A., Horrillo-Caraballo, J. M., Karunarathna, H., & Reeve, D. E. (2020, July). Investigating skimming flow conditions over stepped spillways using particle image velocimetry. In IOP Conference Series: Materials Science and Engineering (Vol. 888, No. 1, p. 012023). IOP Publishing.
26. Tuna, M. C., & Emiroglu, M. E. (2013). Effect of step geometry on local scour downstream of stepped chutes. Arabian Journal for Science and Engineering, 38(3), 579-588.
27. Aminpour, Y., & Farhoudi, J. (2017). Similarity of local scour profiles downstream of stepped spillways. International Journal of Civil Engineering, 15(5), 763-774.
28. Eghlidi, E., Barani, G. A., & Qaderi, K. (2020). Laboratory Investigation of Stilling Basin Slope Effect on Bed Scour at Downstream of Stepped Spillway: Physical Modeling of Javeh RCC Dam. Water Resources Management, 34(1), 87-100.
29. Tabbara, M., Chatila, J., & Awwad, R. (2005). Computational simulation of flow over stepped spillways. Computers & structures, 83(27), 2215-2224.
30. Shahheydari, H., Nodoshan, E. J., Barati, R., & 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.
31. Tabari, M. M. R., & Tavakoli, S. (2016). Effects of stepped spillway geometry on flow pattern and energy dissipation. Arabian Journal for Science and Engineering, 41(4), 1215-1224.
32. Li, S., Zhang, J., & Xu, W. (2018). Numerical investigation of air–water flow properties over steep flat and pooled stepped spillways. Journal of Hydraulic Research, 56(1), 1-14.
33. Hekmatzadeh, A. A., Papari, S., & Amiri, S. M. (2018). Investigation of energy dissipation on various configurations of stepped spillways considering several RANS turbulence models. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 42(2), 97-109.
34. Reeve, D. E., Zuhaira, A. A., & Karunarathna, H. (2019). Computational investigation of hydraulic performance variation with geometry in gabion stepped spillways. Water Science and Engineering, 12(1), 62-72.
35. Arjenaki, M. O., & Sanayei, H. R. Z. (2020). Numerical investigation of energy dissipation rate in stepped spillways with lateral slopes using experimental model development approach. Modeling Earth Systems and Environment, 1-12.
36. Ghaderi, A., Abbasi, S., Abraham, J., & Azamathulla, H. M. (2020). Efficiency of trapezoidal labyrinth shaped stepped spillways. Flow Measurement and Instrumentation, 72, 101711.
37. Li, S., Yang, J., & Li, Q. (2020). Numerical Modelling of Air-Water Flows over a Stepped Spillway with Chamfers and Cavity Blockages. KSCE Journal of Civil Engineering, 24(1), 99-109.
38. Mero, S., & Mitchell, S. (2017). Investigation of energy dissipation and flow regime over various forms of stepped spillways. Water and Environment Journal, 31(1), 127-137.