Model test variations of baffled block installation pattern in energy dissipator USBR type III for reduce flow energy

Abstract

Energy dissipator serves to stabilize the flow of water for preventing any scouring. Scouring can endanger the geometry of downstream river situated at the riverbed and river bank. The change in stream conditions from supercritical to subcritical leads to a hydraulic jump that is used by energy dissipator to reduce the flow energy. Type of energy dissipator which is frequently used is stilling basin equipped with baffled blocks. Baffled blocks serve to generate hydraulic jump and reduce the flow velocity. However, the effectiveness of stilling basin in stabilizing the flow water is lacking. This is proved by the occurrences of scouring on downstream riverbed and riverbank of the weir even though it has been supported by stilling basin. Based on the problem, the research about the installation of baffled block pattern has been done. Model 0 was a model made based USBR type III stilling basin while model 1 was variation model where the baffled block installation was adjusted so that it is located between chute block. The dimension of the baffled block model 1 has modified to adjust the location. The study was conducted by analyzing the hydraulic flow parameters (flow velocity, Froude number and energy specific) on upstream and downstream of energy dissipator. Based on the analysis, it can be concluded that average downstream flow velocity for model 0 was 34.14 cm/sec while for model 1 was 29.18 cm/sec. Thus, model 1 could reduce the flow velocity 1.85% more effectively than model 0. The average downstream Froude number for model 0 was 0.30 while for model 1 was up to 0.26. Thus, model 1 could reduce the Froude Number 0.52% more effectively than model 0. The average energy loss for model 0 was 50.69% whereas model 1 was 51.20%. There is an increase in energy loss by 0.52% from model 0. Thus, model 1 has more effective baffled block pattern installation in stabilizing the water flow than USBR type III model.