Applied Thermodynamics - II, Question Paper of Mechanical Engineering 4th Semester, Download Question Paper Applied Thermodynamics 13

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Total No. of Questions : 09]

B. Tech. (Sem. – 4th)

APPLIED THERMODYNAMICS - II

SUBJECT CODE : ME – 208 (2008 Batch)

 Paper ID : [A0811]

Time : 03 Hours

Instruction to Candidates:

1) Section - A is Compulsory.

2) Attempt any Four questions from Section - B.

3) Attempt any Two questions from Section - C.

Section – A

QI) eox2=20)

a) What do you understand by octane and cetane number rating of fuel.

b) What are the objectives of supercharging the IC engines.

c) Explain why aerofoil blading is needed in axial flow compressors?

d) What is delay period and what are the factors that affect delay period.

e) SI engines are quantity governed while CI engines are quality governed.

Explain. D For the given air flow and pressure ratio the vane type blower needs less work than a roots blower. Give reasons.

g) Define the term slip factor, power input factor.

h) Write down the methods of cooling the turbine blades.

t) Define the term thrust, thrust power of jet propulsion system.

j) State the assumptions made in an ideal cycle analysis of gas turbines.

Section - B

Q2) A six-cylinder gasoline engine operates on four stroke cycle. The bore of each

cylinder is 80 mm and the stroke is 100 mm. At speed Of 4000 rpm the fuel

consumption is 20 kg/hr and the torque developed is 150 Nm. Calculate (i) the

brake power (ii) the brake mean effective pressure (iii) brake thermal efficiency

if calorific value of the fuel is 43000 kJ/kg.

Q3) Discuss the working of vane type blower with neat sketch.

Q4) With the aid of neat diagram, explain the working principle of ramjet engine.

Q5) A flying turbojet engine propels at speed of 880 km/hr and draws air at the rate of 50 kg/s. Isentropic enthalpy drop in the nozzle is 190 kJ/kg and its velocity

coefficient is 0.96. Fuel air ratio used is 0.012. The calorific value of fuel used

is 46000 Kj/kg and combustion efficiency is 95Vo. Find thermal, propulsive

and overall efficiency.

Q6) Define polytropic efficiency of compressor with the help of T-S diagram and

obtain an expression for polytropic efficiency.

Section - C

Q7) A centrifugal compress runs at 16000 rpm and power required to run the

compressor amounts to 2300 kW. The outer diameter of the impeller is 50 cm.

The uniform width of the casing of vortex chamber between impeller and

diffuser is 4 cm. Static conditions at a radius of 27 cm were measured and

it were equal to 2.4 bar and 390 K. Surrounding pressure is lbar. Assuming

slip factor of 0.94, find the mass flow rate of gas, the resultant velocity

and temperature at the given radius of 27 cm. Assume c_p = 1.005 kJ/kgK and

 = 1.4

Q8) The first stage of an axial compressor is designed on free vortex principles,

with no on let guide vanes. The rotational speed is 6000 rpm and the stagnation

temperature rise is 20K. The hub-tip ratio is 0.60, work done factor is 0.93 and

isoentropic efficiency of the stage is 0.89. Assuming an inlet velocity of 140

m/s and ambient conditions of 1.01 bar and 288 K, calculate (i) tip radius and

corresponding rotor air angles, if the Mach number relative to the tip is limited

to 0.95 (ii) mass flow entering the stage (iii) stage stagnation pressure ratio and

power input (iv) rotor air angles at the root section. Assume cp = 1.005 kJ/kgK

and  = I.4.

Q9) In a gas turbine power plant the temperature ratio T_max/ T_min,in is fixed as 4. The system has compression in two stages with perfect intercooling in between the

stages followed by single stage expansion in gas turbine. Isoentropic efficiency

of each compressor and turbine is 0.85 and 0.9 respectively. Minimum

temperature of the cycle is 300K. Assuming the pressure ratio of the cycle as

6. Find the network output, heat input and thermal efficiency of the cycle.

Take P_min = P₁, = 1 bar, c_p = 1.005kJ/kgK and   = l-4.