Hydraulic Structures: Fourth Edition

y 0 to obtain the increase, ∆yya y 0 , for the aerated flow. The inception of aeration occurs at the point where the turbulent ...

SPILLWAYS 217 tially and fully aerated non-uniform flow is beyond the scope of this text but various approaches can be found in, ...

for 0.16S/q1/51.4. For smooth spillways, C0.5027(S/q2/3)0.385 (4.45) for 0.23S/q2/32.3 (qin equations (4.44) and (4.45) is ...

SPILLWAYS 219 For small values of K, equation (4.50) results in V S n 1/ V (^2) q 2/ 2 3 /3  1 c (^1)  2/3 . (4.51) Equati ...

(ramps), offsets, or grooves, or a combination of two or all three of them (Fig. 4.12). The most frequent shape used on spillway ...

SPILLWAYS 221 qa/q0.29(Fr 1)0.62(D/y)0.59 (4.55) where Fr is the Froude number just upstream of the aerator, and DcA/b, with ...

222 DAM OUTLET WORKS Fig. 4.13 Shaft spillway outlets or even a turbine tailrace. The main components and rating curve of the sp ...

SPILLWAYS 223 Fig. 4.14 Shapes of shaft spillways (after Wagner, 1956) approximated by Cd0.773 1 0.4 D H c ; for  D H c  ...

Fig. 4.16 Shaft spillway placed in a cut in the bank (after Novak and Cˇábelka, 1981) Fig. 4.15 Discharge coefficients of shaft ...

SPILLWAYS 225 Although, in some of the older shaft spillways placed well away from the banks and operating under free-flow condi ...

4.7.5 Siphon spillways Siphon spillways are closed conduits in the form of an inverted U with an inlet, short upper leg, throat ...

SPILLWAYS 227 Fig. 4.18 Siphon spillway, Spelga Dam, UK (Poskitt and Elsawy, 1976) increase in specific discharge and the automa ...

4.7.6 Stepped spillways Stepped spillways (ordinary overfall spillways followed by steps on the spillway face) have been used fo ...

SPILLWAYS 229 due to the difficulties in the definition of the onset of skimming flow as well as to possible scale effects. The ...

several configurations; Baker (1994) included in his investigations flat blocks and reinforced grass and reported stability for ...

lower than the upstream water level, inside the dam, with flow passing through the main body of the rockfill (Lawson, 1987). 4.8 ...

Large bottom openings serve as submerged spillways (Section 4.7.7) and their capacity can be used for flushing sediment from the ...

Fig. 4.21 Sainte-Croix arch dam bottom spillway (Thomas, 1976) Fig. 4.22 Bicaz dam outlet works (Novak and Cˇábelka, 1981) ...

faces, at the expense of allowing small negative pressures to develop on them. To prevent the formation of vortices in the water ...

WORKED EXAMPLES 235 Solution Initially, assume a spillway length of 200 m and a constant discharge coeffi- cient of 0.75. Thus, ...