ANNA UNIVERSITY AERO QB

ANNA UNIVERSITY, CHENNAI 25

MODEL QUESTION PAPER

B.E. AERONAUTICAL ENGINEERING, VI SEMESTER

AE 342 - PROPULSION-II

TIME – 3 Hours MAXIMUM : 100 Marks

PART A (10 X 2 = 20 Marks)

ANSWER ALL QUESTIONS

1. Explain the difference between Impulse and reaction blade.
2. How will you classify turbine blade cooling?
3. Draw T-S diagram of Ramjet Engine.
4. Name the components in Pulse Jet Engine.
5. Describe briefly three important application of rocket propulsion
6. Define specific propellant consumption.
7. What are the types of propellant injector?
8. Name any two properties of liquid propellant.
9. Define thrust coefficient.
10. Explain the principles of Nuclear propulsion?

PART B (5 X 16 = 80 Marks)

11 i. Define degree of reaction and prove for 50% of reaction a = ß and ae = ßi
suffix i.e. stands for inlet and exit. 8

ii. At the mean diameter of a gas turbine the blade velocity is 350 m/s. The blade
angles at inlet and exist are 200 and 540 respectively, and the blades at this
section are designed to have a degree of reaction of 50%. The mean radius of the
blades is 0.216m and the blade mean height is 0.07m. Assuring the blades are
designed according to vortex theory calculate.

The flow velocity. 3
The angles of blades at the tip and at the root. 3
The degree of reaction at the tip and at the root of the blades. 2

12 (a) A ram jet engine operates at M = 1.5 at an attitude of 6500m. The diameter of the
inlet diffuser at entry is 50 cm and the stagnation temperature at the nozzle entry
is 1600K. The calorific value of the fuel used is 40 MJ/Kg. The properties of the
combustion gases are same as those of the air [ r = 1.4, R = 2875 / Kgk ]. The
velocity of the air at the diffuser exit is negligible. Calculate



i. The efficiency of ideal cycle 2
ii. Flight spaced 1
iii. Airflow rate 2
iv. Diffuse, pressure ratio 2
v. Fuel air ration 1
vi. Nozzle pressure ratio 1
vii. Nozzle Jet mach number 2
viii. Propulsive efficiency 3
ix. Thrust 2

Assume the following values
?D = 0.90 ?B = 0.98 ?j = 0.96
Stagnation pressure loss in combustion chamber = 0.02 PO2
At z = 6500m the properties of air are
T1 = 245.90 K P1 = 0.44 bar
a1 = 314.50 m/s S1 = 0.624 kg/m3

( OR )

(b) i. With aid of a neat diagram, explain the working principle of ram jet engines 8
ii. Draw the thermodynamic cycle of ram jet engine and derive the equation
for thrust. 8

13 (a). Derive the following relation for the characteristic velocity 8

ao
(i) V* =

(? + 1) /2( ? – 1)
? 2

? + 1



————
v
R T0 M
(ii) V* =


(? + 1) /2 (? – 1)
2
v ?
? + 1



Calculate the values of the characteristic velocity for 8

i. ? = 1.25 M = 18.3 and T0 = 3300 K
ii. ? = 1.33 M = 29.0 and T0 = 3508 K

( OR )

(b) A rocket flies at 10,080 km/hr with an effective exhaust jet velocity of
1400 m/s and propellant flow rate 5 Kg / s. If the head of reaction of the
propellant is 6500 KJ / Kg of the propellant mixture determine

(i) Propulsion efficiency and propulsion power 6
(ii) Engine output and thermal efficiency 6
(iii) Over all efficiency 4

14 (a) I Explain briefly the following terms in solid propellant rocket

(i) Linear burning rate 2
(ii) Combustion rate 2
(iii) Propulsion area ratio 3
(iv) Equilibrium combustion pressure 2
(v) Cigarette burning 3

II Explain briefly what is meant by

(i) Mono propellants 2 (ii) Hypergolic propellant 2

( OR )

(b) i. Draw a neat sketch of a Turbo pump feed system employed in rockets 8
ii. How does cavitation occurs in this system and what measures are taken to
prevent it 8

15 (a) i How is regressive, neutral and progressive burning of the solid
propellant grown achieved? Explain with the aid of diagram. 8
ii. State 5 advantages and 5 disadvantages of solid propellant rocket 8

( OR )

(b) Draw neat sketches, explaining the general working of the following rocket engines.

(i) Hybrid engine 8
(ii) Electrical rocket 8