Question

chanud! Par ritengaalr Alternative a for rectes gual 25 pts) A rectangular channel is 3.50 m wide conveys a discharge of 14.0 m/s at a depth of 2.0 m. It is proposed to reduce the width of the channel at a hydraulic structure. Assuming the transition to be horizontal and the flow to be frictionless determine the water surface elevations upstream and downstream of the constriction when the constricted width is: (a) 3 m. (Plot the specific energy versus depth curves) (b) 2 m. (Plot the specific energy versus depth curves) (c) Define specific energy and explain its relevance in determining critical conditions in a channel flow.

Answer 1

Solution. discharge, Q = 14 M/ depth, y = 20 B = 3.50m yazma 1 Ye= (h L = / 1/3 Discharge per unit wilth 2 40075.com = 1:18M. 1-774 Froud Number. F = Joy 19.8142² & subcritical flow. Critical Width calculation (BG) - E2c = 1.5% = 2 2 1 2 4 / 5 & Ez a lente) 3 > (33* en a { let) • {2+ kryt - 4 leton) 1 B21 = 1 6.299 = 12.51m7

O B2 - 3m > B26= 2.576 No choke condition. . 6 = Ez E-specific energy a you want use these things * (* bitol) = net 3D * x2 - 2:204722 + 2.22 30 372 9.1.536 ANA 4:24 2 x 9.81 3467 I E . ELE2c 2.02 ☺ 2 = 9 B92x Yet Bota ett B: 2m 5 024 2-510 a choke condition a critical & low condition con at section @ B 62 = 2m, q = 2 = 1 4 = 7n/sing Yes (388 1729 15 - 1.77 · Ezca 1.5 ML = 1.50X1.71 = 2.564^. E = ERC

9 = 2.564 o * + yaxsel = 2.564 2 703 2.5645" 2 +1.63120 5 % - 2.2399, 1.0324 B<B2C et Bl 27 YA ötes-sub eritroel 2:29 c m 2.2497 7=297 AT v supercritical q GOEREEL 26.77 -2.56 .: upstream depth = 2-239 - 12.244] and ① specific energy is total energy (Pressure head + velocity head & clatun head) when cladors is taken as zero for reference. The graph of specific energy Vs depth help in determing depth of flow for subcritical and supercritical flow condition.