# JNTU, B.Tech,I-Semester,MECHANICAL AND ELECTRICAL SCIENCE, November ,2008

JNTU, B.Tech,I-Semester,

MECHANICAL AND ELECTRICAL SCIENCE, November 2008

(Civil Engineering)

SET-1

1. (a) Under what situation, two stroke cycle engine is preferred to four stroke cycle

engine.

(b) A 2-stroke C.I engine develops a brake power of 400 kw while its friction power

is 80 kw. The fuel consumption of the engine is 200kg/hr and its calorific value

is 40 MJ /kg. The air-fuel ratio used is 20:1. Find

i. I.P

ii. Indicated thermal efficiency and

iii. brake thermal efficiency.

2. (a) Explain the terms Dry bulb temperature, wet bulb temperature and Relative humidity.

(b) A sling psychometer reads 440c DBT and 500c WBT, calculate the following

without the use of psychometric chart.

i. Specific humidity

ii. Relative humidity

iii. Dew point temperature.

3. (a) What are the different types of flames in gas welding? Discuss them briefly.

(b) What is welding process? Discuss the classification of welding.

4. (a) Discuss with a neat sketch the nomenclature and function of the different

elements of a drill.

(b) Distinguish between drilling and milling.

5. (a) How the optimum depth of cut is determined for the power shovel ?

(b) What types of materials can be handled by Screw Conveyors?

PART-B

1. Explain the construction of a DC machine with a neat sketch.

2. Explain the speed control of dc motors.

3. Draw the general schematic of a single phase transformer and explain its working

principle.

4. The data obtained on 5 KVA, 400V, 3 phase alternator is armature resistance 0.5

ohms/phase

OC Test Field current 1 A, phase voltage = 140V.

SC Test Field current 1 A, line current = 3.6 A.

Determine the full load regulation of alternator at 0.8 pf lagging.