B.E-B.E Aeronautical Engineering Aerospace Propulsion I (Sathyabama University, Chennai, Tamil Nadu-2010)
Friday, 23 August 2013 02:15Duraimani
(Established under section 3 of UGC Act,1956)
Course & Branch :B.E - AERO
Title of the Paper :Aerospace Propulsion – I Max. Marks :80
Sub. Code :526504/626503 Time : 3 Hours
Date :26/04/2010 Session :AN
PART - A (10 x 2 = 20)
Answer ALL the Questions
1. Find the propulsive efficiency of a jet engine moving with 300 m/s at 7000 m altitude with an exhaust gas velocity of 600 m/s.
2. Mention any two important performance characteristics which make turboprop engine superior to turbojet engine.
3. What are the starting problems that occur in supersonic inlets?
4. For a subsonic inlet, draw a graph between Amax/Ai vs. deceleration ratio Ui/Ua for a given CPmax.
5. When does a stage said to be free vortex stage?
6. Define degree of reaction of an axial flow compressor.
7. Mention any two methods employed in flame tube cooling.
8. Compare can and annular type combustors.
9. When do you select variable area nozzle for the aircraft?
10. What is a choked nozzle?
PART – B (5 x 12 = 60)
Answer All the Questions
11. Find the specific thrust and SFC of a simple turbojet engine, having the following component performance at which the cruise speed and altitude are M=0.8 and 10000 m respectively. Select ambient conditions from the gas tables.
Compressor pressure ratio = 8
Turbine inlet temperature = 1200 K
Isentropic efficiency
Of compressor (hc) = 0.87
Of turbine (ht) = 0.90
Of intake (hi) = 0.93
Of propelling nozzle(hj) = 0.95
Mechanical transmission efficiency (hm) = 0.99
Combustion efficiency(hb) = 0.98
Combustion chamber pressure loss DPb 4% of compressor outlet pressure.
(or)
12. Explain with a neat sketch and cycle performance curves the operating principle of a turbofan engine.
13. Derive a relation between minimum area ratio and external deceleration ratio.
(or)
14. Explain in detail about the modes of inlet operation.
15. The following data are suggested as a basis for the design of a single sided centrifugal compressor power input factor Y is 1.04, slip factor s is 0.9, rotational speed 290 Rev/s, Overall diameter of the impeller is 0.5 m, Eye tip diameter is 0.3m, Eye root diameter is 0.15m, Air mass flow m=9 Kg/s, Inlet stagnation temperature = 295 K.
Inlet stagnation pressure = 1.1 bar and Isentropic efficiency h = 0.78.
Determine:
(a) Pressure ratio of the compressor and the power required to drive the compressor assuming that the velocity of the air at the inlet is axial.
(b) Calculate the inlet angle of the impeller at the root and tip radii of the eye assuming that the axial inlet velocity is constant.
(or)
16. Estimate the power required to drive a single – stage axial flow compressor with 50% reaction. The stator outlet and rotor inlet angles are 40° and 60° respectively. The mean radius of the blade configuration is 30 cm. The overall efficiency of the stage is 90%. The hub – tip radius ratio is 0.8. The axial velocity component at design flow rate is uniformly 125 m/s and the inlet air is at 1.01325 bar and 20°C. Draw the velocity triangles and what should the shaft speed be under these conditions?
17. What are all the important factors affecting combustor design?
(or)
18. What are the methods of flame stabilization? What is meant byu flame tube cooling?
19. Explain with neat sketch under, over and optimum expanded nozzle and show the variation of flow properties along the C – D nozzle axis by curves.
(or)
20. Write short notes on:
(a) Thrust Reversal.
(b) Variable area nozzle.
| Earning: ₹ 3.25/- |
