USN

1 P E

PESIT Bangalore South Campus Hosur road, 1km before Electronic City, Bengaluru -100

Department of Basic Science and Humanities

BE I semester

INTERNAL ASSESSMENT TEST 2 Date : 03-10-2016 Marks: 40 Subject & Code : Elements of Mechanical Engineering – 15EME14 Sec : F,G,H,I,J,K

Name of faculty : Prof. TGR, Varun, Shashikumar & Praful Time : 90mins

Note: Answer FIVE full questions, selecting any ONE full question from each part. Marks

PART 1 1 a Explain with a neat sketch the parts and working of a De Laval Turbine. Also draw

the pressure-velocity graph. 6

b Write a short note on function of a piston in an engine cylinder. 2 2 a Explain with a neat sketch the parts and working of a mixed flow water turbine. 6

b Write a short note on function of the two valves in an engine cylinder. 2

PART 2 3 a

Explain with a neat sketch the parts and working of a high head water turbine. 6

b Define stroke volume and indicated power of an engine. 2 4 a

Explain with neat sketch the working cycle of a open cycle gas turbine. 6

b Which engine has a higher compression ratio? Also mention its range. 2

PART 3 5 Write any 6 differences between 4-stroke and 2-stroke engines. 8

6 With the help of a neat sketch explain the working of a two-stroke petrol engine. 8

PART 4 7 Explain with a neat sketch the working of a 4-stroke spark ignition engine. (P-V

Diagram is not required)

8

8 Explain with a neat sketch working of a 4-stroke diesel engine. (No P-V Diagram) 8 PART 5

9 A single cylinder 4-stroke IC engine has a bore of 180mm, stroke of 200mm and a rated speed of 300rpm. Torque on the brake drum is 200 Nm and mean effective pressure is 6 bar. It consumes 4kg of fuel in one hour. The calorific value of the fuel 42000 kJ/kg. Determine a) Mechanical Efficiency b) Indicated Thermal Efficiency c) Brake Thermal Efficiency

8

10 A 4-cylinder two-stroke petrol engine develops 30kW of brake power at 2500rpm. The mean effective pressure on each piston is 8 bar and mechanical efficiency is 80%. Calculate the diameter and stroke of each cylinder, stroke to bore ratio is 1.5. Also calculate the fuel consumption if brake thermal efficiency is 28%. The calorific value of the fuel is 43900kJ/kg.

8

1. (a) Explain with a neat sketch the parts and working of a De Laval Turbine. Also draw the pressure-velocity graph.

1. (b) Write a short note on function of a piston in an engine cylinder.

2. (a) Explain with a neat sketch the parts and working of a mixed flow water turbine.

2. (b) Write a short note on function of the two valves in an engine cylinder.

3. (a) Explain with a neat sketch the parts and working of a high head water turbine.

3. (b) Define stroke volume and indicated power of an engine.

Stroke volume is defined as the volume covered by the piston when it moves from top dead centre to bottom dead centre.

Indicated power is defined as the power developed inside the engine due to the combustion of the fuel.

4. (a) Explain with neat sketch the working cycle of a open cycle gas turbine.

4. (b) Which engine has a higher compression ratio? Also mention its range.

Diesel Engine has a higher compression ratio.

It ranges from 16:1 to 22:1

5. Write any 6 differences between 4-stroke and 2-stroke engines.

6. With the help of a neat sketch explain the working of a two-stroke petrol engine.

7. Explain with a neat sketch the working of a 4-stroke spark ignition engine. (P-V Diagram is not required)

8. Explain with a neat sketch working of a 4-stroke diesel engine. (No P-V Diagram)

10. A 4-cylinder two-stroke petrol engine develops 30kW of brake power at 2500rpm. The mean effective pressure on each piston is 8 bar and mechanical efficiency is 80%. Calculate the diameter and stroke of each cylinder, stroke to bore ratio is 1.5. Also calculate the fuel consumption if brake thermal efficiency is 28%. The calorific value of the fuel is 43900kJ/kg.