Anna University Coimbatore 2009 B.E Electrical and Electronics Engineering Thermal And Fluid Engineering - Question Paper
Q.CODE: 081019
B.E. / B.TECH. DEGREE EXAMINATIONS : NOV / DEC 2009
EEE / EIE BRANCHES 08E302 / 08N302 : THERMAL ENGINEERING AND FLUID MECHANICS TIME : 3 HOURS MAX. MARKS : 100
ANSWER SECTION A AND SECTION B IN SEPARATE ANSWER BOOKS
SECTION A : THERMAL ENGINEERING
ANSWER ALL QUESTIONS
PART A
(5x2= 10)
1. Write the Clausius statement.
2. Define the term COP.
3. What is the thermodynamic process in a Brayton Cycle?
4. What is meant by compression ratio of an engine?
5. Write the applications of reciprocating air compressors.
PART B
(40 Marks)
6. A quantity of air has a volume of 56.5 litres and pressure of 7.03 bar. It
is expanded in a cylinder to a pressure of 1.05 bar. Compute the workdone if the expansion follows the rule pv1 = C (Take y = 1.4) (14)
7. (a) What are the differences between heat pump and refrigerator?
(b) A domestic food freezer is maintained at a temperature of -15C. The ambient air temperature is 30 C. If heat leaks into the freezer at the continuous rate of 1.75 KJ/S, what is the least power required to pump this heat out continuously? (10)
8. An engine working on constant volume has a clearance volume of one litre and stroke volume of six litres. The suction pressure and temperature are 1 bar and 20 C respectively. The pressure at the end of heat addition is 25 bar. Determine i) pressure and volume at salient points of the cycle ii) thermal efficiency and iii) workdone per cycle.
Take Cv = 0.807 KJ/kg k and y = 1.4 (13)
(OR)
9. Explain the working principle of four stroke diesel engine with a neat (13) sketch.
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air enters the impeller radially with a velocity of 7 m/s. Calculate the vane angle at inlet and power required to drive the compressor. (13)
-2- Q.CODE:081019
SECTION B : FLUID MECHANICS ANSWER ALL QUESTIONS PART A
(5x2 = 10)
1. What is the principle of measurement of pressure using manometer?
2. Distinguish between path line and streak line.
3. State impulse momentum principle. Where it is mostly applied?
4. Define unit speed.
5. What is NPSH?
PART B
(40 Marks)
6. (a) Derive an expression for specific speed of a turbine. (8)
(b) A single acting reciprocating pump has a plunger diameter of 250 mm and a stroke of 350 mm. If the speed of the pump is 60 rpm and it delivers water against a total head of 25m, find the theoretical power required to drive the pump. (6)
(OR)
7. (a) Derive the expression for minimum starting speed of a centrifugal (7)
pump.
(b) A Francis Turbine working under a head of 5m at a speed of 210 rpm develops 75kW when the rate of flow of water is 1.8 m3/sec. If the head is increased to 16m, determine the speed, discharge and power. (7)
8. (a) Derive Bernoullis equation along a stream line through Eulers (8)
/
equation.
(b) A converging pipe is 20 cm in diameter at inlet and 10 cm diameter at outlet, 5m in length and inclined at 45to the horizontal. The pipe is carrying water at 24000 litres per minute. The pressure at the inlet is 500 kPa. Find the pressure at the outlet. (5)
(OR)
9. (a) Explain the following : Stream function and Velocity potential. (5)
(b) A main pipe divides into two parallel pipes and again forms a single pipe. The lengths and diameters of the parallel pipes are 1500m and 60 cm and 1500m and 40 cm respectively. Find the flow rate in each parallel pipe if the total discharge in the main pipe is 2000 litres /sec.
Take f for 1st pipe as 0.005 and for the 2nd pipe as 0.006. (8)
10. (a) With a neat sketch explain the working of a Bourdon Tube pressure
gauge. (5)
(b) A plate of size 1.5m x 1.5 m and 2 mm thick weighing 50N is to be lifted through a gap of 2cm filled with oil of viscosity 25 poise and specific gravity 0.9. Find the force and the power required to lift the plate at a constant velocity of 10 cm/s. (8)
(OR)
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3 Q.CODE: 081019
11. (a) A differential U-tube manometer is connected to two pipes whose centres are at 3m difference in height. Higher level pipe is carrying liquid of specific gravity of 0.9 at a pressure of 1.8 bars and another pipe is carrying liquid of specific gravity 1.5 at a pressure of 1 bar. The centre line of the pipe carrying low pressure liquid is 2m above the higher level of mercury in the manometer. Find the difference in level of the mercury in the manometer in cm. (9)
(b) Determine the minimum size of glass tubing that can be used to measure the water level if the capillary rise in the tube is not to exceed 2.5 mm. Surface tension of water in contact with air as
0.0075 kg (f)/m. (4)
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