8_Hydraulics Practice Quiz with Answer and Solution

Refresher - HYDRAULICS Quiz 8
PROBLEM 1-3:

The turbine of a hydrostatic plant is driven by a falling head of water from a
source 30 m. high up through a 600 mm penstock flowing full.

➀ Evaluate the theoretical velocity of water as it hits the turbine blades in m/sec.
➁ Evaluate the theoretical discharge of water in m3/s.
➂ If the turbine is only 70% efficient, estimate the horsepower available from it.

Solution:
➀ Theoretical velocity of water as it hits the turbine blades
V = 2gh
V = 2(9.81)(30)
V = 24.26 m / s

➁ Theoretical discharge of water in m3/s
Q = AV
π
Q= (0.6)2 (24.26) Powerhouse
4 To
transmission
Tansformer
Q = 6.86 m3 / s
lines


Generator
30m
Gate
➂ Horsepower available from it Turbine


Qγ wE Tail water
HP =
746
6.86(9810)(30)(0.70) Bedrock
HP = Penstock Draft tube

746
HP = 1894 hp

, Refresher - HYDRAULICS Quiz 8
PROBLEM 4:


An open cylindrical vessel 0.60 m. in diameter contains water 0.90 m.
deep when at rest. If it is rotated about its vertical axis at speed of 180
rpm, determine the least depth the vessel can have so that no water is
spilled over the sides.


Solution:
ω
2 2
w r
y=
2g
180(2π) y/2
w= y
60
H y/2
w = 18.85 rad/sec 0.90
2 2
(18.85) (0.30)
y=
2(9.81)
y = 1.63 m
0.6
1.63
H = 0.90 + = 1.715 m
2