Question

hydrulics eng problem solve it please

Problem 3: channel by 8ft. The flow is suberitical to lower gular channel is 15ft?is/ft. A vertical drop is used o is suberitical above and below the drop structure. Determine the drop structure without impact blocks for a tailwatr s (d/s water) depth of 3.58t. Make a neat schematic diagram of drop structure and

Answer 1

Ans) Given,

Discharge(q) = 15 ft³/s /ft

Depth to be lowered (h)= 8ft

Tail water depth(y_o) = 3.50 ft

Step 1) Calculate critical depth

Since, flow is subcritical, critical depth (y_c),

y_c = (q²/g)^1/3

= (15²/9.81)^1/3

= 2.838 ft

Step 2) Calculate required tail water depth above the floor of stilling basin :

y2 = 2.15 y_c

= 2.15 x 2.838

= 6.10 ft

Now, distance from the crest down to tail water is required to be calculated :

h2 = h - y_o

= 8 - 3.50

= 4.5 ft

Step 3) Calculate total drop from the crest to stilling basin floor

d = h2 + y2

= 4.5 + 6.10

= 10.60 ft

Step 4) Calculate the basin length :

L_f = [ -0.406] x y_c

V3.195+ 4.36 S(d/c) jx

= 8.695 ft

L_t =[- 0.406] x y_c

V3.195 + 4.368(h2/ye)

= 7.87 ft

Ls = [0.691 + 0.228(] x yc / [0.185 + 0.456(Lt/yc)]

V Lt

= (0.691 + 1.06) x 2.838 / 1.45

= 12.86 ft

L_d = (L_f + L_s)/2

= (7.87+ 12.86)/2

= 10.365 ft

  L_B = L_d + 0.80 y_c + 1.75 y_c

= 10.365 + 0.80(2.838) + 1.75(2.838)

= 17.60 ft

2. LB