Flow Chocking Characteristics of Leak-Floor Flip Buckets
Leak-floor flip bucket is a new type of flip bucket recently proposed. It has the advantages of decreasing flow choking on the bucket in small flow regimes and improving energy dissipation by a typical long-narrow nappe. However, if the structure parameters are designed unreasonably, flow choking may also occur on the bucket if the impact location of the lower jet trajectory is too near to the base of the structure, and will threaten the safety of the dam. The purpose of this paper is to study the critical conditions when flow choking begins to disappear or appear on the leak-floor flip bucket, during the increasing and decreasing discharge regimes, respectively. Five leak-floor flip bucket models were conducted, and one circular-shaped flip bucket was prepared for comparison. The critical conditions were investigated under a systematic variation of the approach flow depth, gap width and gap length. It concludes that the critical Froude numbers are primarily influenced by the relative bucket height and the area ratio of the gap; empirical equations for the prediction of critical conditions are obtained and conformed to the test data reasonably.
KeywordsLeak-floor flip bucket Flow choking Critical condition Dissipater
This research was financially supported by the National Science Foundation. Thanks to the guidance of Professor Jianhua Wu and Fei Ma in Hohai University. Thanks to the proposal of Professor Jiwei Yang in Hebei University of Engineering.
- 2.Juon, R., Hager, W.H.: Flip bucket without and with deflectors. J. Hydraul. Eng. ASCE 126(11), 837–845 (2000). https://doi.org/10.1061/(ASCE)0733-9429(2000)126:11(837)CrossRefGoogle Scholar
- 4.Heller, V., Hager, W.H., Mior, H.E.: Ski jump hydraulics. J. Hydraul. Eng. ASCE 5, 347–355 (2005). https://doi.org/10.1061/(ASCE)HY.1943-7900.0001178CrossRefGoogle Scholar
- 5.Khatsuria, R.M.: Discussion of “ski jump hydraulics” by Valentin Heller, Willi H. Hager and Hans-Erwin Minor. J. Hydraul. Eng. 131(5), 347–355 (2005). https://doi.org/10.1061/(ASCE)0733-9429(2006)132:10(1115)CrossRefGoogle Scholar
- 8.Steiner, R., Heller, R.V., Hager, W.H., et al.: Deflector ski jump hydraulics. J. Hydraul. Eng. 134(5), 562–571 (2008). https://doi.org/10.1061/(ASCE)0733-9429(2008)134:5(562)CrossRefGoogle Scholar
- 10.Pfister, M., Hager, W.H.: Deflector-jets affected by pre-aerated approach flow. J. Hydraul. Res. 1–11 (2012). https://doi.org/10.1080/00221686.2012.657875
- 11.Lucas, J., Hager, W.H., Boes, R.M.: Deflector effect on chute flow. J. Hydraul. Eng. ASCE 139(4), 444–449 (2013). https://doi.org/10.1061/(ASCE)HY.1943-7900.0000652CrossRefGoogle Scholar
- 12.Deng, J., Liu, S.J., Zhou, Z., et al.: A swallowtail—type of bucket. 2009.12.25, Application number: 200910263563.9. (in Chinese)Google Scholar
- 13.Wang, J.M., Duan, S.H., Zheng, J.: Key technical problems in the construction of Jinping I high arch dam. Technical Progress in the Dam Construction and Management, The Chinese Association of Dam, Sichuan China, 2012:11. (in Chinese)Google Scholar
- 14.Chen, X.M., Wang, Z.M., Wang, X.B., et al.: Key techniques in the Nam Ngiep II hydropower construction. Technical Progress of high dam construction and operation management, The Chinese Association of Dam, Guiyang, China, 2014.1016. (in Chinese)Google Scholar
- 15.Deng, J., Yang, Z.L., Tian, Z., et al.: A new type of leak-floor flip bucket. Sci. China Technol. Sci. 1–8 (2015). https://doi.org/10.1007/s11431-015-5925-x
- 17.Liu, Z.R., Jiang, Y.Y., Liu, G.C., et al.: Arc radius and critical jet flow discharges in the ski jump energy dissipaters. Proc. Energy Dissipation Eros. Control 441–448 (1980). (in Chinese)Google Scholar
- 18.Design specification for concrete gravity dams. Water Conservancy Industry Standard of the People’s Republic of China, SL319-2005. (in Chinese)Google Scholar