2010
MECHANICAL ENGINEERING
Paper 1

Time: 3 Hours] Maximum Marks: 300
INSTRUCTIONS
Candidates should attempt all the questions in Parts B However, they have to choose only three questions in Part D. Answers must be written in the medium opted (i.e. English Kannada). This paper has four parts: A B C D 20 marks 100 marks 90 marks 90 marks Marks allotted to each question are indicated in each part. C. or
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f
PART A 4x5=20
Answer each of the following questions in about 50 words. Each question carries 5 marks.
1. Ca) What is meant by Virtual work 5

What is a structure and what is the difference between a machine and a structure 5


What are the different types of followers? Classify them according to the motion of follower" location of axis of the follower and .according to the shape of that part which is in contact with the cam. 5


Cd) What is the difference between brakes and dynamometers What
are the different types of Mechanical brakes 5
j
PARTB 10x10=100
Answer all the following questions. Each question carries 10 marks.
Answers for theory questions are not to exceed about 100 words each.

2. The maximum and minimum speed of a flywheel are .242 T.p.ro. and 238 r.p.m. respectively. The mass of flywheel is 2600 kg and radius of gyration is 1·8 m. 10
Find

Mean speed of flywheel


Maximum fluctuation of energy and


Co-efficient of fluctuation of speed.
3.
An epicyclic gear consists of three wheels Band C as shown in the figure. Wheel A has 72 internal teeth, C has 32 external teeth. The wheel B gears with both A and C and is carried on all: arm which rotates about the centre of A at 18 T.p.ro. If the wheel A is fixed, determine the speed of wheels Band C. 10

4.
A transmission shaft, rotating at 500 T.p.m., drives a milling machine which requires 3-75 kW at 750 T.p.ro. A 300 mm diameter cast iron pulley is mounted on the transmission shaft. A preliminary design proposes using a belt 4·75 mm thick, which has a density of 970·001 kg/rna The Allowable stress is 2000 kPa. Two pulleys rotate in opposite directions and the centre distance of the shaft is 750 mm. The co-efficient of friction is 0·3 for both the pulleys. Determine the width of the belt.



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5.
At a point in a strained material, the normal tensile stresses are 60 N/mm2 and 30 N/mm2. Determine by Mohr's circle, the resultant intensity of stress on a plane inclined at 40° to the axis of the minor stress. Also check the answer analytically. 10

6.
Explain RMS value method and Hz value method to measure the roughness. 10

7.
With the help of a block diagram, explain the working of an electrical comparator. 10

8.
Discuss Sampling plan versus Control charts to control the quality of work in process, either installing the control charts at the machine or inspection of the product by means of a sampling plan. 10

9.
How is machinability connected to tool life? 10

10.
An automotive single-plate clutch consists of a pair of contacting surfaces. The inner outer radii of friction plate are 120 mm and 250 mm respectively. The co-efficient of friction is 0·25 and the total axial force is 15 kN. Calculate the power transmitting capacity of the clutch plate at 500 r.p.m., using 10


Uniform wear theory and


Uniform pressure theory



11.
Explain the terms Spin and Precession as related to Gyroscope. How do they differ from each other? 10


PARTe 6x15=90
Answer all the following questions. Each question carries 15 marks. Answers for theory qustions are not to exceed about 150 words each.
12. Fit a second order polynomial to the data given in the Table shown
below. Also show the error analysis. 15
x·I Yi
0 2·1
1 7·7
2 13·6
3 27·2
4 40·9
5 61·1

Also find the standard error and correlation Comment on the result.
13. It is required to drill a hole of 1·69 mm diameter to a depth of 7·32 mm in steel sheet using R circuit by electro-discharge machining method using a brass electrode. The surface finish required is to be 20 micron. Determine the source voltage to be set up for a condenser and resistance setting of 120 micro-farads and 100 ohms respectively. Also find out the time required for drilling. Assume sparking period 100 ft-sec. 15
Given that
(il Surface roughness K1(l/2 CU2)/S tpKg microns where Kv K2 and
K3 are constants and their values for brass electrode and steel
work piece are 13, 0·45, and 0·22 respectively.
C capacitance of the condenser in farads
U voltage across the capacitor
tp pulse duration in Il-sec.

Metal removal rate 1·42 t,U2 mmSfsec charging time).
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14/1 6
14. With the help of a ductile material. neat sketch explain the stress and strain curve of a 15
15. Explain what is Jig and Fixture. Enumerate the operational factors that must be considered to achieve the most efficient clamping for holding jig or fixture. 15
16. Define the term UWhirling speed of a shaft". Prove that the whirling speed of a shaft in T.p.S. (revolutions per second) is given by the relation, N 0·4985 C -J8 15
17. Explain with the help of sketch how the energy distribution takes place in explosive forming process to various components. 15

PARTD

Answer any three of the following questions. Each question carries 30 marks. Answers for theory questions are not to exceed 300 words each.
18.
What do you mean by 'steering gear' Derive an expression for the fundamental equation of correct gear. 30

19.
With the help of a neat sketch explain the working of Electrochemical Machining. What are its advantages and limitations Discuss about Electrochemical Machining suitability and applications. 30

20.
A composite bar made up of aluminium and steel, is held between two supports as shown in the figure.



Aluminium har 25mm$
600mm 300mm

The bars are stress free at a temperature of 38°C. What will be the stresses in the two bars, when the temperature is 21°C, if 30

The supports are unyielding and


The supports come nearer to each other by 0·1 mm. It can be assumed that the change of temperature is uniform all along the length of the bar.


Take E for steel as 210 kN/mm2, E for aluminium as 74 kN/mm2 and co·efficient of expansion for steel as 11·7 x 10-6 per co-efficient of expansion as 23·4 x 10-6 per °e.
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1411 8 I
21. A number of masses (say four masses) are attached to a shaft which is rotating at an angular speed of ro rad/s. If all the masses are in the same plane, then describe the analytical and graphical method of balancing these four masses by a single mass only. 15
Derive an expression for the height of Watt that the height of the governor is inversely square of the speed of the Governor. governor and prove proportional to the 15
22. Outline necessary steps in connection with' using the control charts for X and R for any quality characteristic of mam.1factured product. 10
What factors determini;ng. should be taken into consideration by a firm when 20
The sample size
The manner in which items should be selected for in the sample inclusion
The frequency of sampling
The operatious to be controlled by control charts for variables

1 14/2
2010
MECHANICAL ENGINEERING
Paper 2

Time: 3 Hours J Maximum Marks: 300
INSTRUCTIONS
Candidates should attempt all the questions in Parts B However, they have to choose only three questions in Part D. This paper has four parts: Answers must be written in the medium opted (i.e. English Kannada). A B C D 20 marks 100 marks 90 marks 90 marks Marks allotted to each que8tion are indicated in each part. C. OT
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PART A 4x5=20
Answer all the following questions in about 50 words. carries 5 marks. Each question
1. Enumerate the factors which contribute to internal concerned with summer comfort air conditioning. load gain as 5
Define the following non-dimensional numbers CD Grashof Number 5
Raleigh Number Explain what is meant by transient heat conduction. 5
Explain what is meant by carburetion. 5

•

Answer all the following questions. Each question carries 10 marks.
Answers for theory questions are not to exceed about 100 words each.

2.
With the help of a diagram explain the terms transmissivity, absorptivity, reflectivity. When are the surfaces said to be perfect transparent, perfect reflector, perfect absorber?

3.
Consider hypothetical heat engines, Band each operating between 1000 K and 300 K. When each engine involves itself with a heat interaction of 1000 kJ with the high temperature reservoir, it is claimed that while A develops a work of 600 kJ, Band C develop 700 and 800 kJ. Use the Carnot statement and mention whether engines Band Care reversible, irreversible or impossible. 10

4.
A closed adiabatic wall chamber of height 3 m contains 9 kg of dust uniformly distributed. The kinetic energy of the dust is 100 J as the dust is moving about the chamber. Determine the changes in energy as the dust settles to the bottom. 10

5.
Explain the working of the Carnot cycle with the help of T-s diagram. 10

6.
Explain the terms After burning, Preignition as concerned with Sl engine. 10


10

7. Classify the turbines on the basis of, 10

Head and quantity of water available.


Hydraulic action of water.


Direction of flow of water with respect to runner.


Specific speed of turbines.


8.
Define the critical thickness of insulation. Derive an expression for thickness of insulation for a cylindrical object. 10

9.
Establish the following expression for air -water vapour mixture,


Pv
specific humidity is given by 0·662 where PIS
P v
b
v partial pressure of water vapour and Ph is barometric pressure.
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For a sample of air having 22'C DBT, relative humidity 30 per cent at barometric pressure of 760 mm of Hg, calculate Humidity ratio,
Vapour density and Enthalpy using the psychrometric chart.

ENTHALPY kJlkg
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10. Draw a neat sketch of the pool boiling cnrve and mark all the regimes. 10
11. With the help of a neat sketch, explain the development of a boundary layer when a fluid is flowing with a velocity on a flat plate. 10
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PARTC 6x15=90
Answer all the following questions. Each question carries 15 marks. Answers to theory questions are not to exceed about 150 words each.
12. Air at a rate of 8·5 kg/s and having inlet temperatnre 135°C is to be
cooled in a cross flow heat exchanger (Single pass). Water is used for
cooling operation at a rate of 0·6 kg/s and is available at 20°C. Both
fluids can be treated as unmixed. The overall heat transfer coefficient for the system is 210 W/m2 K. The surface area of the is 200 m2.
Calcnlate the ontlet temperatnre of air, total heat transfer rate. Take specific heat of water 4180 J/kg specific heat of air 1005 J/kg K. 15
EFFECTIVENESS -CROSS FLOW, BOTH FLUIDS UNMIXED
100
90
80


Eo<
Z
70
riI
U

riI
60

en
50
riI
Z 40
u
riI
30

riI
20
10
0


0.2 0.30.4 0.6 0.81 2 3 4 6 810 NUMBER OF TRANSFER UNITS, NTU
13. Ooe end of a long rod is inserted into a furnace while the other projects
into ambient air. Under steady state the temperature of the end of the rod is measured at two points 75 mm apart and found to be 125°C and SS·5°C, respectively, while the ambient temperature is 20°C. If the rod is 25 mm in diameter and convective heat transfer coefficient is 23·36 W/m2 find the thermal conductivity of the rod material. 15
14. The resisting force F of a supersonic plane during the flight can be considered as dependent on the length of aircraft L. velocity air viscosity Il. air density p and bulk modulus of air K. Express the functional relationship between these variables and the resisting force. 15
15. Draw a neat sketch of a Nuclear Reactor and explain the function of each component. 15
16. Explain the working of·Benson Boiler with the help of a sketch. 15
17. With the help of a neat sketch explain the working of a solar still. 15

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PARTD 3x30=90
Answer any three of the following questions. Each question carries 30 Answers to theory questions are not to exceed about 300 words each.
18. In an engine working on dual cycle the temperature and pressure at the beginning are 27°C and 1 bar respectively. The compression ratio is 12. The maximum pressure is limited to 70 bar and the total heat supplied is 1500 kJlkg. Find. the following 30

Pressure and temperature at all salient points.


Air standard efficiency.


Mean effective pressure.


19. With the help of neat sketches explain the pressure field due to a source of disturbance when

Source Mach number IS less than 1.


Source Mach number IS equal to l.


Source Mach number IS greater than l.


Source is stationary. 30


20. A single stage air compressor delivers air at 6 -bar. The pressure and temperature at the end of suction are 1 bar and 27°C. It delivers 1·5 m3 of free air per minute when the compressor is running at 350 rpm. The clearance volume is of the stroke volume. The free air condition are 1·013 bar and 15°C. The index of compression and expansion 1·3. Find

the volumetric efficiency.


the bore and stroke of the cylinder if both are equal.


the power required if the mechanical efficiency is 80%. :W


21.
Witb the help of a neat sketch explain the working of an Ejector refrigeration system. Show the states on the diagram. 30

22.
Discuss the effect of the following on the performance of a vapour compressIOn. system 30


Effect of suction pressure


Effect of delivery pressure


Effect of superheating


Effect of subcooling of liquid