ocd51 ame 6005 thermofluids & control system · ocd51 university of bolton western...
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OCD51
UNIVERSITY OF BOLTON
WESTERN INTERNATIONAL COLLEGE FZE
BENG (HONS) MECHANICAL ENGINEERING
SEMESTER ONE EXAMINATION 2015/2016 ADVANCED THERMOFLUIDS & CONTROL SYSTEM
MODULE NO: AME 6005
Date: Saturday 16 January 2016 Time: 1:00 – 4:00 INSTRUCTIONS TO CANDIDATES: There are 6 questions. Answer 4 questions. All questions carry equal marks. Marks for parts of questions are shown
in brackets. CANDIDATES REQUIRE : Thermodynamic properties of fluids
tables are provided Take density of water = 1000 kg/m3
Formula sheets provided
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Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Q1.
a ) For the laminar viscous flow through a circular pipe, derive an expression for
the velocity distribution and shear stress distribution through it. Also prove the
following:
i) The velocity variation is parabolic
ii) The shear stress variation across the section of the pipe is linear
(10 marks)
b) What power is required per kilometre of a line to overcome the viscous
resistance to the flow of glycerine through a horizontal pipe of diameter 120mm
at the rate of15 litres/s?Take µ =8 poise and kinematic viscosity(ν)= 6 stokes.
(5 marks)
c) An oil of viscosity 0.2Ns/m2 and relative density 0.9 is flowing through a circular
pipe of diameter 65mm and of length 400m.The rate of flow of fluid through the
pipe is 4 litres/s. Determine the following:
i) Pressure drop in a length of 400m
ii) Shear stress at the pipe wall.
(10 marks)
Total 25 marks
Please turn the page
Page 3 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Q2.
a) Water at 25oC flows at a rate of 45 litres/s in a cast iron pipe of 40cm diameter
and 120m length. The system includes a sudden entrance (ke= 0.5) and a gate
valve (kg=0.15).Determine the head loss of the pipe.
Given the kinematic viscosity of water at 25oC = 1 x 10-6 m2/s.
The surface roughness value for cast iron = 0.26mm.
(15 marks)
b) The external and internal diameters of a collar bearing are 300mm and 250mm
respectively.Between the collar surface and the bearing, an oil film of thickness
0.25mm and of viscosity 0.9 poise,is maintained.If the shaft is running at 270
r.p.m ,evaluate the following:
i. Torque generated
(5 marks)
ii. Power lost in overcoming the viscous resistance of the oil.
(5marks)
Total 25 marks
Please turn the page
Page 4 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Q3.
(a) Steam enters an engine at a pressure of 12MPa absolute and 550oC.
It is exhausted at 2 bar. The steam at exhaust is 0.9 dry. Find the following:
i) Drop in enthalpy
(5 marks)
ii) Change in entropy
(5 marks)
iii) Sketch the process in T-S diagram
(2 marks)
(b) A closed system contains air at pressure 1.5 bar, temperature 300K and
volume 0.025 m3. This system undergoes a thermodynamic cycle consisting
of the following three processes in series:
Process 1-2: Constant volume heat addition till pressure becomes 4 bar.
Process 2-3: Constant pressure cooling.
Process 3-1: Isothermal heating to initial state
i. Evaluate the work done for each process (3 marks)
ii. Evaluate the heat transfer for each process (3 marks)
iii. Evaluate the change in entropy for each process (3 marks)
iv. Represent the cycle on T-S and p-v plot. (4 marks)
Take Cv =0.718kJ/kgK and R= 287 J/kgK
Total 25 marks
Page 5 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Please turn the page
Q4.
(a) An industrial control system shown in Figure Q4 uses a PID controller.
Gc(s) Gp(s) +
-
Input(s) Output(s)
Figure Q4
Where
)1(10)( sKds
KisGc ,
sssGp
6
4)(
2
i. If Ki=0, determine the value of Kd for critical damping.
(4 marks)
ii. With Kd as determined in (i) determine the limiting value of Ki such that
stability is maintained.
(6 marks)
iii. Find the Ki for a parabolic input (Ѳi = ) if GC(s) is a PI controller and the
steady state error is less than 5%. (3 marks)
iv. Design a PID controller by determining Kp and Kd (using the Ki obtained
from (ii) above) to achieve maximum overshoot less than 20 % and settling
time ts less than 4 seconds.
(9 marks)
(b) Analyse how system dynamics is affected by PID parameters Kp, Ki, Kd .
(3 marks)
Page 6 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Total 25 marks
Please turn the page
Page 7 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Q5.
(a) Obtain the state space model of a simplified industrial robotic system shown in
Figure.5(a)
Figure .Q5.a
(15 marks)
(b) The state equations for a mechanical system are given below.
Analyse controllability and observability of the system. (10 marks)
Total 25 marks
Please turn the page
M1 M2
K1 K2
B1 B2
y1 y2
u
Page 8 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Q6
(a) An industrial manufacturing system controlled by a digital controller is shown in
Figure Q6.
Figure Q6
(i) Discuss the roles of ADC, Digital Computer, and DAC.
(3 marks)
(ii) Illustrate stability criteria for sampled-data control systems.
(3 marks)
(iii) Analyze the stability of the sampled control system shown in Figure.6 (b),
when the sampling time is (i) T=0.5 sec, (ii) T=1 sec.
(19 marks)
Figure Q6.iii
Total 25 marks
END OF QUESTIONS
s( )
R(s) E(s) E*(s) C(s)
T. + -
A/D Digital
Computer
D/A Plant
Sensor
i/p o/p
Page 9 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Please turn the page
FORMULA SHEET
P = F/A
ρ = m/v
m. = ρAV
P = Pg + Patm
P = ρ gh
Q- W = ΔU + ΔPE + ΔKE
W = PdV
P Vn = C
W = P (v2 – v1)
du/dy =
1 -n
V P - V P =W 2211
Page 10 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
V
V PV = W
1
2ln
Q = Cd A √2gh
12 21
g
ghgCV m
.ΔMΔt
ΔMF
F = ρ QV
τ = -(∂p/∂x) r/2
Re = V D ρ/
∆p = (32VL)/D2
U = 1/(4) -(∂p/∂x) (R2-r
2)
dQ = du + dw
du = Cv dT
dw = pdv
pv = mRT
h = hf + xhfg
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Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
s = sf + xsfg
v = x Vg
hm w - Q...
3
2
2
R
RL
LF
n
T
dQds
1
2n12 L
T
TCSS pL
2
1L n12
P
PmRSS
f
fg
pLgT
hTCS
273L n
f
pu
f
gf
pLT
TC
T
hfTCS nn L
273L
1
2n
1
2np12
P
PMRL
T
TL MCSS
Page 12 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Page 13 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
sCDFD
2u 2
1
suFL
2
LC 2
1
)( gZPds
dS p
L
pDQ
128
4
gD
L
Rh f
2
v64 2
Re
16f
g2d
fLv4h
2
f
g
Khm
2
v2
g
VVkhm
2
2
21
H
L
T
T1
η= (h1 – h2)/(h1- hf 2)
T
QSSSgen )12
Page 14 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
geno STSSTUUW 02121 )(
)( 12 VVPWW ou
)()()( 21021021 VVPSSTUUWrev
)()()( 00 oVVPoSSTUU
genToSI
F = τ πDL
1000
60
2
4
2
4
1
2
1
2
gQHp
RRt
NT
R
RL
uLF
t
V
rV
n
Page 15 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Transfer Function for Blocks with feedback loop
G(s) = )()(1
)(
sHsGo
sGo
(for a negative feedback)
Steady-State Errors
)]()(1
1[lim
0s
sGse i
os
ss
(For the closed-loop system with a unity feedback)
Performance measures for second-order systems
Maximum Overshoot in % = exp %100))1(
(2
Settling time ts = n
4
Characteristic equation 1+GH=0
s2+2 n s+ n2=0
Observability Test Matrix = [ CT
: A
T C
T]
Controllability Test Matrix = [ B :
AB]
Page 16 of 17
Western International College FZE BEng (Hons) Mechanical Engineering Semester 1 Examinations 2015/16 Advanced Thermo fluids & Control System Module No. AME 6005
Laplace Transforms Z Transforms A unit impulse function 1
A unit step function s
1
Exponential Function
A unit ramp function 2
1
s