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[Total No. of Pages: 03

~Total No. of Questions : 09]

B. Tech. (Sem.

- 4th)

APPLIED rHERMODYNAMICS SUBJECT CODE : ME-208

- II

Paper ID : [A0811] [Note: Please fill subject code and paper ID on OMR)

Time: 03 Hours Instruction

Maximum

Marks:

60

to Candidates:

1) 2)

Section - A is Compulsory. Attempt any Four questions from Section - B.

3)

Attempt any Two questions from Section - C.

Section - A (10 x 2 =20)

Ql) a)

What do you understand by air injection and solid injection system?

b)

What is the purpose -of engine testing?

c)

Discuss the term squish, swirl.

d)

What are the various factors that influence the name speed?

e)

Differentiate between a flywheel and govemer. .

t)

Define the term pressure coefficient, prewhirl.

g)

What do you mean by surging and choking?

h)

Define effectiveness of regenerator.

i)

Define the term take off thrust and propulsive power of jet propulsion system.

j)

What are the various assumptions made in practical cycle analysis in gas turbines?

M-858[1859]

P.T.o.

Section

-B (4 x 5 = 20)"

Q2)

Find the air fuel ratio of four stroke, singl~-cylinder,air cooled engine with fuel consumption time for 10cc as 20As and air consumption time for O.lm3 as 16.3s. The load is 17kg at the sp~edof3000rpm. Find also brake specific fuel consumption in g/k wh and brake thermal efficiency.Assume the density of air as 1.175kg/m3and specific gravity of fuel to be 0.7. The lower heating value of fuel is 43MJ/kg and dynamometer constant is 5000.

Q3)

Free air of 30 m3/min is c
Q4)

The effective jet exit velocity framjet engine is 2700m/s. The forward flight velocity is 1350m/s and the air flow rate is 78.6kg/s. Calculate a) thrust b) thrust power c) propulsive efficiency.

Q5)

What is rocket propulsion? Compare the working ofliquid and solid propellant rockets.

Q6)

Why non-dimensional parameters are used to predict the performance characteristics of compressor? 'Derive these, parameters from the concept of dimensional analysis.

Section - C (2 x 10 Q7)

M-858

= 20)

A centrifugal compressor has to deliver 6kg/s of air with pressure ratio of 4: 1at 17500tpm. Initial conditions are static air at 1bar and 15°C.Assuming an adiabatic efficiency of 78%, ratio of whirl speed to tip speed 0.94 and neglecting all other losses, calculate the tip speed, diameter and rise in total pressure. Also, determine the external diameter of eye forwhich the internal diameter is 12cm and the axial velocity at inlet is 150m/sec. Assume cp=1.005kJ/kgK and y=1.4.

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An axial flow compressor has an overall pressure ratio of 4 and mass flow rate of3kg/s. Ifthe polytropicefficiencyis 880/0andthe stagnationtemperature rise per stage must not exceed 25K,calculate the number of stages required and pressure ratio of first and last stages. Assume equal temperature rise in all stages. If the absolute velocity approaching the last rotor is 165m/s at

Q8}

.

an angle of 20° fromthe axial direction,the work done factoris 0.83,the velocity diagram is symmetrical, and the mean diam~ter oflast stage rotor is 18cm, calculate the rotational speed and length of the last stage rotor blade inlet to the stage. Ambient conditions are 1.01 bar and 288K.

Q9}

In an open cycle, gas turbine plant works between the pressure limits of 1 bar and 4bar and temperature limits of300K and 1000K. Two compressors having equal pressure ratios are used with perfect intercooler between their stages, each having isoentropic efficiency of 80%. The air on leaving the second cQmpressor is passed through regenerator of 65% effectiveness before entering to the combustor. The products of combustion are expanded in single stage gas turbine having an isoentropic efficiency of 85%, upto the lowest pressure and exhaust is passed through the regenerator before being exhausted finally to the atmosphere. The air-fuel ratio is 100:1. For the air mass flow rate of 10kg/s calculate a) compressor and turbine work b) calorific value of fuel used if the combustion efficiency is 95% c) net power developed and thermal efficiency of the plant. Assume and y= 1.4. cp(au. )= 1.01 and cp(gas)= 1.13 kJ/kgK ...,

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M-858

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