Other Bachelor Degree-Other Bachelors Degree GAS DYNAMICS AND JET PROPULSION (Karunya University, Coimbatore-2012)
Saturday, 24 August 2013 10:34anudouglas
Karunya University
(Karunya Institute of Technology and Sciences)
(Declared as Deemed to be University under Sec.3 of the UGC Act, 1956)
Supplementary Examination – June 2012
Subject Title: GAS DYNAMICS AND JET PROPULSION Time: 3 hours
Subject Code: 09ME207 Maximum Marks: 100
Answer ALL questions
(Use of approved gas tables permitted)PART – A (10 x 1 = 10 MARKS)
1. Define Stagnation enthalpy.
2. What is meant by Reference Velocities?
3. Why are diffusers employed in flowing gas?
4. The stagnation state was defined for the ________.
5. State any two assumptions made while deriving the equation for Isothermal flow.
6. Define Rayleigh line.
7. Define Diffuser efficiency.
8. When is the oblique shock formed?
9. Write the equation for Ideal efficiency of the Ramjet.
10. State the two types of Solid propellants.
PART – B (5 x 3 = 15 MARKS)
11. Write short notes about Crocco number.
12. Write short notes about Flow through Diffusers.
13. Write short notes about Fanno line.
14. Write the equation for the maximum possible heat transfer at a Mach number.
15. Define propulsive efficiency and Thermal efficiency.
PART – C (5 x 15 = 75 MARKS)
16. Air (γ=1.4, R=287.43 J/kg K) enters a straight axisymmetric duct at 300 K, 3.45bar and 150m/s and leaves it at 277 K, 2.058bar and 260 m/s. The area of cross-section at entry is 500cm2. Assuming adiabatic flow determine, (a) Stagnation temperature, (b) Maximum velocity, (c) Mass flow rate and (d) Area of cross-section at exit.
(OR)
17. If the condition of the standard atmosphere at the mean sea level is given by p0=1.0133bar, T0=288.2K and μ0=1.79x10-5kg/ms determine pressure, temperature, density and viscosity at altitudes of 10,000m and 15,000m.
18. Air is discharged from a reservoir at p0=6.91bar and t0=325°C through a nozzle to an exit pressure of 0.98 bar. If the flow rate is 3600 kg/hr determine for isentropic flow, (i) Throat area, pressure and velocity, (ii) Exit area, Mach number and (iii) Maximum velocity.
(OR)
19. Derive the equation for Entropy in Steady one-dimensional flow.
20. Air enters a long circular duct (d=12.5 cm, ḟ=0.0045) at a mach number 0.5, pressure 3.0bar and temperature 312K. If the flow is isothermal throughout the duct, determine (a)The length of the duct required to change the mach number to 0.7, (b)Pressure and Temperature of air at M=0.7, (c)The length of the duct required to attain limiting Mach number, and (d)State of air at the limiting Mach number.
[P.T.O]
(OR)
21. A combustion chamber in a gas turbine plant receives air at 350K, 0.55bar and 75m/s. The air-fuel ratio is 29 and the calorific value of the fuel is 41.87 MJ/kg. Taking γ=1.4 and R=0.287 kJ/kg K for the gas determine, (a) The initial and final Mach numbers, (b) Final pressure, temperature and velocity of the gas (c) Percent stagnation pressure loss in the combustion chamber and (d) The maximum stagnation temperature attainable.
22. The state of a gas (γ=1.3, R=0.469 kJ/kg K) upstream of a normal shock wave is given by the following data, Mx=2.5, px=2bar, Tx=275K, Calculate the Mach number, pressure, temperature and velocity of the gas downstream of the shock.
(OR)
23. A jet of air at a mach number of 2.5 is deflected inwards at the corner of a curved wall. The wave angle at the corner is 60°. Determine the deflection angle of the wall, pressure and temperature ratios and final Mach number.
24. A rocket flies at 10,080 kmph with an effective exhaust jet velocity of 1400 m/s and propellant flow rate of 5.0 kg/s. If the heat of reaction of the propellants is 6500 kJ/kg of the propellant mixture determine, (a) Propulsion efficiency and propulsion power, (b) engine output, thermal efficiency and (c) Overall efficiency.
(OR)
25. The diameter of the propeller of an aircraft is 2.5m. It flies at a speed of 500 kmph at an altitude of 8000m. For a flight to jet speed ratio of 0.75, determine (a) The flow rate of air through the propeller, (b) Thrust produced, (c) Specific thrust, (d) Specific impulse and (e) The thrust power.
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