UNIVERSITY OF BOLTON SCHOOL OF ENGINEERING BENG (HONS) IN MECHANICAL ENGINEERING SEMESTER 1EXAMINATION 2017/2018

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1 ENG00 UNIVERSITY OF BOLTON SCHOOL OF ENGINEERING BENG (HONS) IN MECHANICAL ENGINEERING SEMESTER EXAMINATION 07/08 ADVANCED THERMOFLUIDS & CONTROL SYSTEMS MODULE NO: AME6005 Date: 8 January 08 Time: INSTRUCTIONS TO CANDIDATES: There are SIX questions. Answer ANY FOUR questions. All questions carry equal marks. Marks for parts of questions are shown in brackets. This examination paper carries a total of 00 marks. All working must be shown. A numerical solution of a question obtained by programming an electronic calculator will not be accepted. CANDIDATES REQUIRE: Thermodynamic properties of fluids provided Formula Sheet provided Take density of water as 000 kg/m 3

3 Page 3 of 8 Q a) Steam at 0 bar has a specific volume of m 3 /kg, using the property tables find the: i) Temperature ii) Enthalpy iii) The internal energy (0 marks) b) kg of steam at 7 bar and entropy of 6.5kJ/kg K is heated reversibly at constant pressure until the temperature is 50 o c. calculate the heat supplied and show on a T-S diagram the area which represents the heat flow. (5 marks) Total 5 marks Q a) explain with the aid of diagram the simple Rankine cycle. ( marks) b) A collar bearing has external and internal diameters 00 mm and 60 mm respectively. The collar at the bearing surfaces are separated by an oil film mm thick. Find the power lost in overcoming friction when the shaft is rotating at 50 rpm. Take the dynamic viscosity as 0.9 N s/m. (3 marks) Total 5 marks Q3 a) Water flow in a circular conduit where there are different diameters. Diameter D = m changes into D = 3m. The velocity in the entrance profile was measured as 3 m/s. Determine: i) The discharge at the outlet ii) The mean velocity at the outlet iii) The type of flow in both conduit profiles Take the kinematic viscosity as 4 ˣ 0-6 m /s (0 marks) Question 3 continues overleaf Please turn the page

4 Page 4 of 8 Question 3 continued b) A prototype valve which will control the flow in a pipe system converting paraffin is to be studied in a model. The pressure drop P is expected to depend upon the gate opening h, the overall depth d, the velocity v, the density ρ and viscosity μ. Perform dimensional analysis to obtain the relevant non dimensional groups. (5 marks) Total 5 marks Q4 A PID controller designed to control a position of a moving mechatronic system is shown in Figure Q4. The transfer function of the plant is G p ( s) s(0s 6) Input(s) + Gc(s) Gp(s) Output(s) - Figure Q4 The design criteria for this system are: Settling time < 3.5 sec Overshoot < 5% Steady state error < 5% (for a unit parabolic input = /s 3 ) a) Design a PID controller to determine the parameters Kp, Ki, and Kd and clearly identify the design procedure. (5 marks) Question4 continues overleaf Please turn the page

5 Page 5 of 8 Question 4 continued b) If a velocity feedback is introduced into Figure Q4 and suppose Gc(s) = 5, i) draw a block diagram with the velocity feedback and explain the effects on a control system of including the velocity feedback. (4 marks) ii) determine the velocity gain Kv for the damping ratio to be increased as 0.8. (6 marks) Total 5 marks Q5 Figure Q5 shows a manufacturing system which includes a machining centre, a sensor system, and a controller. Machining Centre Gp(s) Sensor System Gs(s) Controller Figure Q5 A manufacturing system The machining centre (an analogue system) is controlled by the controller (a computer numerical control). The sensor system (an analogue system) detects the machining conditions and feedback the detected information to the controller. a) Draw a closed-loop control system, with the help of a block diagram, for the manufacturing system shown in Figure Q5. Clearly identify all the

6 Page 6 of 8 components and explain how the whole closed-loop control system works. (6 marks) Question 5 continued Question 5 continues overleaf Please turn the page b) If the manufacturing control system s resolution required is 4 mv, and the range of sensor system varies between -8 Volt to +8 Volt, i) Design an Analogue to Digital Converter with suitable bits for the manufacturing controller. (4 marks) ii) What integer number represented a value of +4 Volts? iii) What voltage does the integer 800 represent? ( marks) ( marks) c) If the manufacturing controller consists of a Digital to Analogue Converter with zero order element in series with the machining centre which has a transfer function G p ( s) s( s 3) Figure Q5 (c) shows the system. i) Find the sampled-data transfer function, G(z) for the computer control system. The sampling time, T, is 0.5 seconds. (8 marks) ii) Find the steady-state error for the computer control system, if the system subjects a step input. (3 marks)

7 Page 7 of 8 Input + - Output Figure Q5 (c) Total 5 marks Please turn the page Q6 A translational mechanical system is shown in Figure Q6.

8 Page 8 of 8 K C M C Y M Y F Figure Q6 A Translational Mechanical System (a) Derive the differential equations describing the behaviour of the system. (8 marks) (b) (c) Select the state variables and transfer the differential equations obtained from Q6(a) above to the relevant first-order differential equations. ( marks) Determine the state space equations and system matrices A, B, C and D, where A, B, C, and D have their usual meaning. (9 marks) Question Q6 continues overleaf Please turn the page Question 6 continued d) Briefly explain the following three approaches for the analysis and design of closed loop control systems:

9 Page 9 of 8 i) The Laplace transfer function ii) The frequency responses technique iii) The state space technique (6 marks) Total 5 marks END OF QUESTIONS

10 Page 0 of 8 FORMULA SHEETS P V - P V W = n - W = P (v v) W = PV V ln V Q = Cd A gh V g m C g h g F F = ρ QV ΔM Δt Re = V L ρ/ dq = du + dw du = cu dt dw = pdv pv = mrt h = hf + xhfg s = sf + xsfg v = x Vg. ΔM. Q -. w. mh

11 Page of 8 F L R L n R3 dq ds T S T S CpL Ln T S g C pl L n T h 73 T fg f S C pl L n Tf hf 73 T f g C pu L n T T f S S MC p L n T T MRL n P P F D CD u s F L C L u s S p d ds ( P gz) D 4 p Q 8L 64 L v h f R D g 4fLv hf dg f 6 Re

12 Page of 8 K h m g v k V V h m g T T L H S gen S S ) Q T U UTo ( S S) T Sgen W 0 W u W P ( V V) o W rev ( U U) T0 ( S S) P0 ( V V ) ( U U0) T( S S0) Po( V Vo ) I ToS gen

13 Page 3 of 8 V r V t Lu F R Ln R T p N 60t gqh 000 R 4 R 4 G(s) = G(s) = Go( s) Go( s) H( s) Go( s) Go( s) H( s) (for a negative feedback) (for a positive feedback) Steady-State Errors e lim[ s( G ( s)) ( s)] (for an open-loop system) ss s0 O i e e e ss ss ss lim[ s s0 G o i ( s)] (for the closed-loop system with a unity feedback) ( s) lim[ s i ( s)] (if the feedback H(s) ) s 0 G ( s) G ( s)[ H( s) ] G ( s) lim[ s d ] (if the system subjects to a disturbance input) s0 G ( G ( s) ) Laplace Transforms A unit impulse function

14 Page 4 of 8 A unit step function s A unit ramp function s First order Systems O O G ss ( e t / ) (for a unit step input) t / AG ( e ) (for a step input with size A) ss ( t) G o ss ( ) e ( t / ) (for an impulse input) Second-order systems d dt o do n no b o n dt o( s) G( s) ( s) s i bon s n n i dtr = / dtp = P.O. = exp ( ) 00% ( ) 4 ts = n d = n(- ) PID Controller GPID = Kp + Ki/s + Kds

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18 Page 8 of 8 DIMENSIONS FOR CERTAIN PHYSICAL QUANTITIES Quantity Symbol Dimensions Quantity Symbol Dimensions Mass m M Mass /Unit Area m/a ML - Length l L Mass moment ml ML Time t T Moment of Inertia I ML Temperature T θ Velocity u LT - Pressure /Stress p /σ ML - T - Acceleration a LT - Strain τ M 0 L 0 T 0 Momentum/Impulse mv MLT - Force F MLT - Energy - Work W ML T - Power P ML T -3 Elastic Modulus Flexural Rigidity Shear Modulus Torsional rigidity E ML - T - EI ML 3 T - G ML - T - GJ ML 3 T - Moment of Force M ML T - Stiffness k MT - Angular momentum - ML T - Angular stiffness T/η ML T - Angle η M 0 L 0 T 0 Flexibiity /k M - T Angular Velocity ω T - Vorticity - T - Angular acceleration α T - Circulation - L T - Area A L Viscosity μ ML - T - Volume V L 3 First Moment of Area Second Moment of Area Kinematic Viscosity τ L T - Ar L 3 Diffusivity - L T - I L 4 Density ρ ML -3 Specific heat- Constant Pressure C p L T - θ - Friction coefficient Restitution coefficient Specific heat- Constant volume f /μ M 0 L 0 T 0 M 0 L 0 T 0 C v L T - θ - Note: a is identified as the local sonic velocity, with dimensions L.T -

UNIVERSITY OF BOLTON WESTERN INTERNATIONAL COLLEGE FZE BENG (HONS) MECHANICAL ENGINEERING SEMESTER ONE EXAMINATION 2015/2016

UNIVERSITY OF BOLTON WESTERN INTERNATIONAL COLLEGE FZE BENG (HONS) MECHANICAL ENGINEERING SEMESTER ONE EXAMINATION 2015/2016 UNIVERIY OF BOLON OCD5 WEERN INERNAIONAL COLLEGE FZE BENG (HON) MECHANICAL ENGINEERING EMEER ONE EXAMINAION 05/06 ADVANCED HERMOFLUID & CONROL YEM MODULE NO: AME 6005 Date: aturday 6 January 06 ime: :00