Question

4.68. Water is released under a gate in a 0.5-m-wide rectangular flume as shown in Figure 4.36. The water behind the gate has a depth of 2 m (at Section 1), and the gate is opened such that the depth of flow just downstream of the gate (at Section 2) is 12 cm. Find the height, h, of the step such that a hydraulic jump occurs at Section 2, and the flow is choked by the step. Estimate the rate at which energy is lost under this condition. Gate Step 2 m Flow - Figure 4.36: Flow choked by a step

Answer 1

solutions i Bro.sma Cuide rectangulara 2. Is Gate 14 .BG Hi 5 Que from the gate flow = a, .. 018 we know theet. Q = 2 caiß. izg H, = 2-0.12 = 61.88meet cari - H₂=com. Q = 2X1X015 Jag [222_4.8891] Ta = 0.37 will bec) Vi = velocity at seem Vi = Bioin = 6.169 msec, 6p = 0.12 For = b = 6:169 = 5.686 forom hydraulic-jumbe y = -1 #1+8 0.5% 0.12 2 rit V1 +8*5.6862 = 42 0.12 2 b o . í Hz = 0.9im

y = 0.gi or step. for soe Initial energy before Ex= 42.no estava Ez = 0,91 +_0:37 cm Dil Ex 0.5 Frost - JE 1. Form = 0.272 <1 Supbcritical flow.. For about to chodking condition of yl= ye Ec = 1.59( 95 -0.37 = 0.74 EE 1.5x (Dutyy 10 points Ec = 0.573 m. so h (minimum height for choking) hizo En-Ec tart = -0.573 Winner Th=0.427 n. la Energy loss in thy chaulic Jump. Fre e 1.728 m inim - 1.128 me T!: ugyana