MARKING GUIDELINE
NATIONAL CERTIFICATE
FLUID MECHANICS N6
9 April 2020
This marking guideline consists of 6 pages.
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MARKING GUIDELINE
-2FLUID MECHANICS N6
QUESTION 1
o.
za
F
H
P
Q
O
B
M
L
N
J
D
A
C
G
I
K
E
QUESTION 2
Q
m
0,0725 m3/s

et
P
0,0725
31,321
i
0,00661
0,00661 3 000
19,846 m
2.2.1
A
½π 3,42 2
19,057 m2
2.2.2
P
½ 2π 3,42
10,944 m
2.2.3
m

Tv
2.2
AC
[17]

0,0875 m
Q
(17 × 1)
C
ap
2.1
er
s.
c
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.14
1.15
1.16
1.17
31,321

(9)
6,84 0,1  OR A
2 0,1  OR P
½
19,057 m2
½π 6,84
10,944 m
6,84 0,1 
2 0,1 
1,741 m
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2.2.4
Q
AC
19,057
75

21,355 m3/s
21 354,592 ℓ/s
(4 × 2)
0,75

5,425 m/s
600
450 mm2
103
0,00244
450
10‐6
0,00244 m3/s
ρQ
2.3.2
5,425
za
2.3.1
(6)
o.
2.3
(8)
5,425
er
s.
c
13,244 N
hL
2.3.3
(2)
h 1–
1,852 1 – 0,92 
0,352 m

h
2.4.1
a
0,785
v

(1)
et
P
2.4.2
(4)
ap
2.4
1,852 m
(2)
163,363 d
(2)


Tv
2.4.3
2.4.4
S
πdL
π
52
d
Pr
200

320,513
d
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
756,544 mm
(3)
[37]
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QUESTION 3
3.1
3.1.1
Q
ALSE
0,6
1
3

0,0518 m3/s
51,836 l/s
P
za
3.1.2
(3)

Reduced capacity or pressure and failure to deliver water
Loses water after starting
Pump overloads driver
Pump vibrates
Water hammer
Slip
Cavitation
3.3.1
Ha
ω2R
er
s.
c
3.3







ap
3.2
o.
434,097 kW
(Any 5 × 1)
et
P
hf
(5)
0,2275
0,567 m
3.3.2
(3)
(3)


Tv
0,00525 m
Q
OR
Va
ALSE
Va
0,2275
V 0,38 m/s
1
1
V

hf

0,00525 m
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3.3.3
ω2R
Ha
0,2275
0,567 m
Q
Va
ALSE
Va
0,2275
v
1
V
1

0,38 m/s
o.
hf
QUESTION 4
4.1
4.1.1
V1
er
s.
c

0,00656 m
ap
0,368 m/s
z1 – He
z2 
et
P
2 – 24
4.1.2
P
(4)
[25]
V2
m/s
d1
za
3.3.4
(3)
0
224 mm
(8)
ρgQHe
1 000
9,81
0,417
24
Tv
98,1 kW
4.2
(3)
4.2.1
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
80,381 m/s
(2)
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U
P
Q
0,5 V
VA
0,5 80,381 
80,381
40,191 m/s
1,420 m3/s 
ρQU V – U 1
103
1,420

ncosy
40,191 80,381–40,191 1
0,9cos 180°–160° 
4,235 MW
4.2.3
η
V–U 1
(6)
ncosy
100%
0,9cos 180° – 160°
Tv
et
P
ap
er
s.
c
86,832%
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100%
o.
80,381 – 40,191 1
za
4.2.2
TOTAL:
(2)
[21]
100