Elements of Mechanical Engg. - Jan 2013

First Year Engineering (P Cycle) (Semester 2)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS (1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks. 1 (a) (i) Hydro energy is considered as ____________.
(a) Tidal Energy (b) Heat energy (c) Indirect Solar energy (d) Solar Energy(1 marks) 1 (a) (ii) The primary source of solar energy are:
(a) Heliochemical process (b) Helioelectrical process (c) Heliothermal process (d) All of these(1 marks) 1 (a) (iii) Lancashire boiler is a ___________ boiler.
(a) Water tube (b) Fire tube (c) Gas tube (d) Air tube(1 marks) 1 (a) (iv) The temperature at which water starts to boil in static pressure is ____________.
(a) Sensible heat (b) Saturation temperature (c) Wet steam temperature (d) Dry steam temperature(1 marks) 1 (b) Find the total enthalpy of 0.6 kg of steam with an initial dryness fraction of 0.7 is heated at a constant pressure of 7 bar till its temperature rises to 250°C. Assume CPS = 2.25 KJ/KgK. From steam table, at 7 bar, hf=679.1 KJ/Kg. hfg=2064.9 KJ/kg, Tsat=165°C.(6 marks) 1(c) Explain with a neat sketch, the working principle of Lancashire boiler.(10 marks) 2 (a) (i) It is an example of reaction turbine.
(a) De-Leval turbine (b) Kaplan turbine (c) Flow turbine (d) Pelton wheel(1 marks) 2 (a) (ii) Open cycle turbines uses _______________ as the working substance.
(a) Ammonia (b) Nitrogen (c) Air (d) CO₂(1 marks) 2 (a) (iii) ____________ is an example for reaction water turbine.
(a) Pelton wheel (b) Francis turbine (c) Kaplan turbine (d) Both B and C(1 marks) 2 (a) (iv) Method of improving efficiency by successive stages in a turbine is ___________.
(a) governing (b) Compounding (c) Supercharging (d) Turbocharging(1 marks) 2 (b) With a neat sketch explain the working of open cycle gas turbine.(8 marks) 2 (c) Sketch and explain the working of reaction steam turbine with the help of pressure and velocity profile diagram.(8 marks) 3 (a) (i) The motion of a piston is ______________.
(a) Rotory (b) Oscillatory (c) Rectilinear (d) Circular(1 marks) 3 (a) (iii) The power measured in the crankshaft of engine is ____________.
(a) Indicated power (b) Brake power (c) Horse power (d) Torque(1 marks) 3 (a)(ii) Diesel engine is also called as
(a) 4-stroke engine (b) 2-stroke engine (c) C.I. engine (d) S.I. engine(1 marks) 3 (c) A 4-cylinder two stroke petrol engine develops 30 kW at 2500 rpm. The mean effective pressure on each piston is 8 bar and the mechanical efficiency is 80%. Calculate the diameter and stroke of each cylinder, stroke to bore ratio 1.5. Also calculate the specific fuel consumption if brake thermal efficiency is 28%. The calorific value of fuel is 43900 KJ/kg.(8 marks) 3(a)(iv) __________ is fed into the diesel engine through the inlet valve.
(a) Fuel (b) Diesel (c) Air fuel mixture (d) Air(1 marks) 3(b) With the help of a line diagram,explain the working of a two-stroke petrol engine. (8 marks) 4(a) (i) _____________ is the heart of the refrigerator.
(a) Compressor (b) Condenser (c) Expansion valve (d) Evaporator (1 marks) 4(a)(ii) The ratio of heat absorbed in a system to work supplied is ____________.
(a) Refrigeration effect (b) COP (c) Ton of refrigeration (d) Coding effect(1 marks) 4(a)(iii) In a refrigerator exchange of heat takes place in ______________.
(a) Condenser (b) Evaporator (c) Compressor (d) Both A and B(1 marks) 4(a)(iv) _____________ is the refrigerant used in vapour compression refrigerator.
(a) Ammonia (b) Air (c) Freon-12 (d) Nitrogen(1 marks) 4(b) Explain with a neat sketch the working of vapour compression refrigerator(8 marks) 4(c) With a neat sketch explain the working of a typical room air conditioner(8 marks) 5(a)(i) _____________ objects are produced in engine lathe.
(a) Plane objects (b) Curved objects (c) Circular objects (d) None of these(1 marks) 5(a)(ii) Taper turning is an operation of producing ___________ on a work piece.
(a) Tapping (b) Reaming (c) Taper (d) Boring(1 marks) 5(a)(iii) Flute in a twist drill is used for,
(a) Flow of coolant (b) Removal of material (c) Easy removal of curl chips (d) All of these(1 marks) 5(a)(iv) ___________ is not a drilling operation.
(a) Taper turning (b) Reaming (c) Knurling (d) Turning(1 marks) 5(b) Explain with a schematic diagram, show how a centre lathe is specified(8 marks) 5(c) How are counter sinking and counter boring operation done on a drilling machine? Explain with suitable sketches(8 marks) 6(a)(i) Milling cutter is a ____________.
(a) Multipoint cutting tool (b) Abrasive cutter (c) Single point cutting tool (d) Metal removing machine(1 marks) 6(a)(ii) Milling is a ________________.
(a) Metal removal process (b) Metal cutting process (c) Metal joint process (d) None of these(1 marks) 6(a)(iii) ______________ is a natural abrasive mineral consists of aluminium oxide.
(a) Diamond (b) Corundum (c) Emery (d) Aluminium nitrate(1 marks) 6(a)(iv) Grinding is also called as ______________.
(a) Turning (b) Metal cutting (c) Abrasive machining (d) Lapping(1 marks) 6(b) Sketch and explain, the principle and working of a horizontal milling machine.(8 marks) 6(c) With a neat sketch, explain the surface grinding machine(8 marks) 7(a)(i) Welding is a _____________ process used for metals.
(a) Metallurgical joining (b) Forged forming (c) Mechanical joining (d) Adhesive bonding(1 marks) 7(a)(ii) Gas welding is a __________________ method of joining two metals.
(a) Fission (b) Fusion (c) Gas reaction (d) Oxidizing(1 marks) 7(a)(iii) Lubricants are used to reduce the _____________ in machines.
(a) Efficiency (b) Effectiveness (c) Friction (d) Torque(1 marks) 7(a)(iv) In thrust bearing the bearing pressure will be ______________.
(a) Radial (b) Circular (c) Axial (d) Centrifugal(1 marks) 7(b) With a neat sketch, explain the working of oxy-acetylene gas welding(8 marks) 7(c) List the important properties of a good lubricant(8 marks) 8(a)(i) The ______________ motion is the simplest form of transmitting power with minimum loses.
(a) Rotational (b) Rectilinear (c) Oscillatory (d) None of these(1 marks) 8(a)(ii) _______________ is called as positive drive mechanisms.
(a) Belt drive (b) Chain drive (c) Gear drive (d) Both B & C(1 marks) 8(a)(iii) ______________ type of gear drive is used for transmitting power between two perpendicular shafts.
(a) Bevel gear (b) Elliptical gear (c) Helical gears (d) Spur gear(1 marks) 8(a)(iv) For power transmission _____________ is the most suitable power transmission.
(a) Belt drive (b) V-belt drive (c) Rope drive (d) Gear drive(1 marks) 8(b) Derive an expression for length of a belt in an open drive system(8 marks) 8(c) Two spur gears A and B connect two parallel shafts that are 500 mm apart. Gear A runs at 400 rpm and gear B at 200 rpm. If the circular pitch is 30 mm, calculate the number of teeth on gears A and B(8 marks)