INSTITIÚID TEICNEOLAÍOCHTA, SLIGEACH
INSTITUTE OF TECHNOLOGY, SLIGO
School of Engineering and Design
Head of School: Ms Una Parsons
Exam Series: Semester 2 (Summer) Academic Year 2016/2017
Module Title: Module Code:
Hydraulics 302 HYD07005
Programme Code(s): Programme(s) Name(s) Year(s) FT /PT
(if applicable)
SG_ECIVL_BO7 B.Eng in Civil Engineering (Ord) L7 Year 3 FT/PT
SG_EENV_BO7 B.Eng in Enviromental Engineering (Ord) L7 Year 3 FT/PT
Internal
Examiner(s): Mr. John Casserly Charted Engineer, B.E., M.Sc.,MIEI
External
Examiners: Mr. Liam McCarton.
Mr. Danny Groarke.
Instructions to Candidates
Time Allowed: 2 Hours
Number of Questions on Paper: 4
Number of Questions to be attempted: 3
Compulsory Question: None
Any Other Special Instructions: None
Question 1
a) If the head loss hL in a pipe network carrying a flow Q may be taken as KQ2 show
that the head correction factor in an iterative loop balance calculation for a network
of pipes is
Q (hL )
2 L
h
Q
(8 marks)
b) An idealised water supply network shown in figure question 1, has peak demands
at nodes as indicated in m3/s. The value of K for each pipe is 1000s/m5 except for
pipe BE which has a K value of 7500s/m5. The supply pressure head at A is 50m
above ground elevation for the area served, which may be assumed to be flat and
level. Calculate the water pressure head under each node under peak demand
conditions , using two rounds of iteration.
(12 marks)
SUPPLY A B C
0.02 0.03 0.03
0.02
0.02 0.02 0.03 0.03
F E D
Figure Question 1
3
(all flow rates are in m /s)
Question 2
a) Explain what you understand by the following terms, (i) Adiabatic
Conditions, (ii) Isothermal Conditions, and (iii) Mach Number.
(6 marks)
b) A 450mm diameter natural gas pipeline has an operating pressure of 110bar and
discharges to a reservoir with a pressure 90bar. The pipes operating temperature
is 15°C.
i) Estimate the average flow velocity and Mach number for the pipeline.
ii) Estimate the mass flow rate in the pipeline.
(you may use the following data and equations (without derivation))
P .R.T
P0 1 ( 1)
1 ( ).M 2
P1 2
a .R.T
Gas data at 1 atmosphere and zero degrees Celsius
R 287 J /( kg.K ) c p cv
cp
1.4
cv
(14 marks)
Question 3
3a) Define briefly what you understand by the following terms:
i) Transitional turbulent flow
ii) Rough turbulent flow
iii) Smooth pipe law.
(3 marks)
3b) Explain each of the terms in the following formula relating to laminar flow in
pipelines:
32. .V .L
hlf
.g.D 2 (Hagen Poisseulle Formula)
(where the symbols have their usual meanings.)
(5 marks)
3c) It is required that heavy crude oil of density 900kg per cubic metre and a
viscosity of 0.125 pa.s, is to be pumped a distance of 2km at a rate of 10litres per
second through a HPPE pipe with a limited operating pressure of 20 bar. You
may assume that the pipeline is flat and that you can ignore entry and exit
velocities and shock losses. Select a suitable pipeline size for the project
(12 marks)
Question 4
a) Show that the following formula is dimensionally correct;
T W 2 Th2
Where;
W is the weight of fluid above the object and
Th is the horizontal thrust exerted by the fluid on the
object.
_
You may note that the total thrust T = ρ.g.A.Y (where the symbols
have their usual meanings).
(4 marks)
b) A sluice gate which is 3m in width consists of a quadrant of a circle of
radius 1.5m pivoted at its centre O, (see figure question 4). The
centre of gravity of the sluice gate acts through a point 0.6m both
vertically and horizontally below the origin. If the gate weighs 6000kg,
calculate the magnitude and direction of the resultant force acting on
the gate as a result of the fluid. Estimate the turning moment about
the origin required to open the gate.
5m
1.
R=
Figure Question 4
(16 marks)
