The purpose of the study was to investigate the effects of shape variations of weirs and stilling basin type USBR-I on the length of the hydraulic jump and energy loss. The crest of the weir is an important part of dam construction as it releases water from the upstream side of the dam. If not designed properly, a dam can create supercritical flow downstream of the weir, leading to a hydraulic jump that can cause local scour downstream of the weir. Therefore, it is essential to consider the dam’s purpose, as it affects the flow conditions downstream of the weir. The study employed primary data from laboratory testing using a recirculating flume instrument of 10.0 m long, 0.30 m wide channel, and 0.60 m flume height. The tests were conducted by making variations in the form of test objects, namely ogee crest weirs, 1 radius round type weirs, and 2 radius round type weirs using the USBR-I stilling basin type. The tests were conducted using five different variations of flow rates, ranging from 3000 cm3/s to 5000 cm3/s. The data was then analyzed using equations and graphical representations to produce research findings and compared with crest variations. The study found that the length of the hydraulic jump (Lj) was significantly affected by the variations in the dam crest. The maximum discharge was observed in the round type 1 radius dam crest, with a hydraulic jump length of 125 cm. The 2 radius round type dam crest had the longest Lj of 136 cm, followed by the ogee type dam crest with the longest Lj of 142 cm. Furthermore, the study found that the variation of the dam crest had a significant impact on energy loss (hf). The 2 radius round type dam crest had the most significant energy loss (hf) value, with an average hf of 31,429 cm. The ogee type dam crest had an average hf of 31.404 cm, and the round type 1 radius dam crest had an average hf of 30.456 cm. Therefore, the 2 radius round type dam crest was found to be the most efficient in reducing energy loss. In conclusion, the study demonstrated that variations in the dam crest have a significant impact on the length of the hydraulic jump and energy loss. The 2 radius round type dam crest was found to be the most efficient in reducing energy loss. These findings can be used to design dams and weirs that are more efficient and cost-effective.
Author(s) Details:
Jaji Abdurrosyid,
Department of Civil Engineering, Engineering Faculty, Universitas Muhammadiyah Surakarta, Jl. Ahmad Yani Tromol Pos1, Pabelan Surakakarta-57102, Indonesia.
Edi Purwanto,
Department of Civil Engineering, Engineering Faculty, Universitas Muhammadiyah Surakarta, Jl. Ahmad Yani Tromol Pos1, Pabelan Surakakarta-57102, Indonesia.
Renaningsih,
Department of Civil Engineering, Engineering Faculty, Universitas Muhammadiyah Surakarta, Jl. Ahmad Yani Tromol Pos1, Pabelan Surakakarta-57102, Indonesia.
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