Page - 1083 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 4 Rounded bottom end of the vertical shaft Existing design (Q10) Updated design (Q10) COMBINED EFFECT OF THE SPILLWAY AND BOTTOM OUTLETS The physical model allowed testing the effect of combined bell-mouth spillway and two bottom outlets operation. This scenario was tested for the extreme flow of 1 in 1000 years and it was found that the space at the junction of bottom outlets and the spillway tunnel is more aerated, when bottom outlets are in operation (Fig. 5). The use of bottom outlets at extreme flow rates is not recommended based on the model results. These flow rates surcharge the spillway shaft and unfavorably reduce the capacity of the whole hydraulic system. Fig. 5 Bottom left outlet pipe in operation 1083