| Summary: | ABSTRACT
Supercritical water jet resulted from a vertical gate (underflow) has high erosion power which causes a problem on scouring downstream of the gate especially on erodible bed. Therefore river bed protection from local scouring is needed. A method for control this local scouring is using apron and energy dissipators downstream of the gate.
This research was conducted in four models which include apron without energy dissipators, apron with end sill only, apron with baffle blocks only, apron with combination of end sill and baffle blocks. The four models were tested experimentally with variation of flow discharge and tailwater level. Scour parameters covering maximum scour depth, distance of maximum scour and length of the scour hole were observed. The relation between flow parameters and these scour parameters were evaluated.
The result showed that 97% of scour depth occured in the first 150180 minutes. Maximum scour depth, distance of maximum scour and length of the scour hole increased with the difference in height between upstream and downstream water levels. Empirical relations for maximum scour were evaluated for each models. End sill gave smallest scour depth reduction (18.71%) but it made maximum scour depth location away from apron. Baffle blocks gave a significant scour depth reduction (37.4%). Application both end sill and baffle blocks result the highest reduction up to 62.63%.
Keywods : local scouring, vertical gate, energy dissipators
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