Post graduate exam in hydraulic 2018 minya university

1. Final Exam.- 1 -
El Minia University Advanced Water Structures II
Faculty of Engineering Date: July 1, 2018
PostgraduateExam. Time: 3 hours
 Answer all the following questions,
 Assume any missing data reasonably,
 Net sketches and clear dimensions are required.
‫ورقتني‬ ‫يف‬ ‫ئةل‬‫س‬‫أ‬ ‫مخسة‬ ‫من‬ ‫مكون‬ ‫الامتحان‬
‫وهجان‬ ‫حدههام‬‫إ‬ ،
&
" ‫إلعظمي‬ ‫إدلرجة‬
0
7
“
Question No 1 (10 Marks)
A rectangular swimming pool 1.0 m deep at one end and increases uniformly in
depth to 2.6 m at the other end. The pool is 8 m wide and 32 m long and is emptied
through an orifice of area 0.225 m2
, at the lowest point in the side of the deep end
(see the shown sketch). Taking Cd for the orifice as 0.60, find from the first
principles:
 The time for the depth to fall by 1.0 m,
 The time to empty the pool completely.
Question No 2 (15 Marks)
A pump on test at its designed speed of 1450 rpm gave the following results:
H (ft) 27 25 21.5 17.5 13.5 8 3
Q (gal/min) 0 250 500 750 1000 1250 1375
 (%) 0 20 42 60 69 66 61

2. Final Exam.- 2 -
The pump is to run continuously at its design speed and is to deliver water through
40 ft of pipe against a static lift of 5 ft. The only pipes available are 6in, 8in and
10in diameter all with f =0.028.
i. Which will be the most suitable pipe for this duty?
ii. Estimate the horse power required to drive the pump and calculate the
specific speed of the pump at maximum efficiency?
iii. Plot on the square paper an estimated head-quantity (Q) curve for the
pump running at 1000 rpm.
Question No 3 (15 Marks)
“Net sketches are required in your answer”
a.
 What is the tractive force? State the forces acting on a particles to check the
bank Stability in a Trapezoidal Channel?
 Mention the meaning of erosion, and its relation with velocity?
 Define the terms maximum and minimum permissible velocities.
 Why are locks and dams necessary for navigation?
 What is meant by meandering?
b. Design a straight trapezoidal channel for a design discharge of 10 m3
/s. The
bottom slope is 0.00025 and the channel is excavated through fine gravel
having particle size of 8 mm. Assume the particles are moderately rounded
and the water carries fine sedimentation at low concentration. (Take the critical
shear stress = 7.20 N/m and free board = 1.40 m).
Question No 4 (15Marks)
a) What is the purpose of diffusers for wastewater?

3. Final Exam.- 3 -
b) A round jet of wastewater is discharging upward from near the bottom of a bay
that is 120 m deep. The jet is 0.3m in diameter, and the discharge rate is
2m3
/s.
 What are the velocities along the axis of the jet at vertical distances of
30m and 60m from the origin of the jet (Z = 30 m and Z = 60 m?),
 What are the velocities at these same Z-direction but at a radial distance
of 6m from the axis of the jet?
(The density of the wastewater is 1000kg/m3
and the density of the water
in the bays is 1026kg/ m3
)
Question No 5 (15 Marks)
a) How is the following defined (beside net sketches):
Braiding Channel and when it occurs,
Functions of Surge Tanks and surge tank types,
Best efficiency point of a pump,
What is a water hammer? and the things that alter it.
b) When shaft spillways are often selected for a project? Give a typical shaft
spillway through abutment of a dam.
c) What are the major components of a shaft spillway?
d) Explain by sketches the three types of possible flow regimes in vertical shaft
spillway, and draw the characteristic of a rating curve for a morning gallery
spillway in a curve?
With Best Wishes and
Good Luck

4. Final Exam.- 4 -
F
w, h
F
Uplif
t

5. Final Exam.- 5 -
Forces and loads acting the dam:
Fi : Ice Load (for cold climates and
Fi1, and Fi2 for reservoir and tail water in the downstream, respectively)
Fw: Water force produced by earthquake (Fw1, and Fw2 for reservoir and tail
water in the downstream, respectively)
Fwh: Hydrostatic force produced by water in the reservoir and tail water in the
downstream (Fwh1, and Fwh2)
Fwv: Water load produced by water weight (Fwv1, and Fwv2 for reservoir and tail
water in the downstream, respectively)
Fu : Uplift force produced by groundwater (since the tail water in the downstream,
the diagram of uplift force will be in trapezoidal shape)
W : The weight of the dam (W1, W2, W3…Wn)
Fd : Earthquake forces (Fdh1 and Fdv1: horizontally and vertically)
The values of the forces (total vertical and total horizontal, and moments):
Forces Moment Arm about “o” Moment “kN.m ”
𝑾, 𝑭 (2) 𝑋𝒘 (3) 𝑊 × 𝑋𝒘
𝑾𝟏 = 𝟎. 𝟓 × 𝟔 × 𝟕𝟎 × 𝟐𝟒
= 𝟓𝟎𝟒𝟎 𝒌𝑵
𝑋𝒘𝟏 =
𝟏
𝟑
× 𝟔 + 𝟒 + 𝟒𝟓
= 𝟓𝟏𝒎
5040 × 51 = 257040 𝑘𝑁
𝑾𝟐 = 𝟒 × 𝟕𝟎 × 𝟐𝟒 = 𝟔𝟕𝟐𝟎 𝒌𝑵
𝑋𝒘𝟐 =
𝟏
𝟐
× 𝟒 + 𝟒𝟓 = 𝟒𝟕𝒎 6720 × 47 = 315840 𝑘𝑁
𝑾𝟑 = 𝟎. 𝟓 × 𝟒𝟓 × 𝟕𝟎 × 𝟐𝟒
= 𝟑𝟕𝟖𝟎𝟎 𝒌𝑵
𝑋𝒘𝟑 =
𝟐
𝟑
× 𝟒𝟓 = 𝟑𝟎𝒎 37800 × 30 = 1134000 𝑘𝑁
𝑭𝑾,𝒉 = 𝟎. 𝟓 × 𝟔𝟓 × (𝟏 × 𝟗. 𝟖𝟏)
× 𝟔𝟓 ≅ 𝟐𝟎𝟕𝟐𝟓 𝒌𝑵
𝑋𝒘,𝒉 =
𝟏
𝟑
× 𝟔𝟓 = 𝟐𝟏.𝟔𝟕𝒎
20725 × 21.67
= 449111 𝑘𝑁
𝑭𝑾,𝒗 = 𝟎. 𝟓 × 𝟔 × (𝟏 × 𝟗. 𝟖𝟏)× 𝟔𝟓
≅ 𝟏𝟗𝟏𝟓 𝒌𝑵
𝑋𝒘,𝒗 =
𝟐
𝟑
× 𝟔 + 𝟒 + 𝟒𝟓
= 𝟓𝟑 𝒎
1915 × 53 = 101495 𝑘𝑁
𝑭𝑼 = 𝟎.𝟓 × 𝟓𝟓 × (𝟏 × 𝟗. 𝟖𝟏)× 𝟔𝟓
≅ 𝟏𝟕𝟓𝟑𝟓 𝒌𝑵 𝑋𝒘,𝒗 =
𝟐
𝟑
× 𝟓𝟓
= 𝟑𝟔.𝟔𝟕 𝒎
17535 × 36.67
= 643010 𝑘𝑁

6. Final Exam.- 6 -
∑ 𝑀 = 449111 + 643010 = 1092121 𝑘𝑁. 𝑚
𝑜
∑ 𝑀 = 257040 + 315840 + 1134000 + 101495 = 1808375
𝑜
𝑘𝑁. 𝑚
∑ 𝐹𝑉 = 5040 + 6720 + 37800 + 1915− 17535 = 33940 𝑘𝑁
∑ 𝐹ℎ = 20725 𝑘𝑁

7. Final Exam.- 7 -

8. Final Exam.- 8 -

9. Final Exam.- 9 -

10. Final Exam.- 10 -
Note: The pumping well itself can be taken as one of the observation wells, in
which case r1 equals the radius of the pumping well r.

11. Final Exam.- 11 -

12. Final Exam.- 12 -

13. Final Exam.- 13 -

14. Final Exam.- 14 -
‫المياه‬ ‫منسوب‬
‫الجوفية‬
‫تطفو‬ ‫التي‬

15. Final Exam.- 15 -
The vadose zone