### AE1351 PROPULSION-II Questions Bank 2014

Anna University, Chennai

Part-B UNIT I

AIRCRAFT GAS TURBINES

1. Describe the working of axial flow turbine stage with neat sketch.

2. Describe the working of radial flow turbine stage with neat sketch.

3. Discuss the limiting factors in turbine design.

5. What are the factors considered to select blade profile, pitch and chord?

6. In a single stage impulse turbine the nozzle discharge the fluid on to the blades at an angle of

65 degrees to the axial direction and the fluid leaves the blades with an absolute velocity of 300 m/s at an angle of 30 degrees to the axial direction. If the blades have equal inlet and outlet angles and there is no axial thrust, estimate the blade angle, power produced per kg/s of the fluid and blade efficiency.

7. A multi stage turbine is to be designed with impulse stages, and is to operate with an inlet pressure and temperature of 6 bar and 900 K and an outlet pressure of 1 bar. The isentropic efficiency of the turbine is 85 %. All the stages are to have a nozzle outlet angle of 75 degrees and equal outlet and inlet blade angles. Mean blade speed of 250 m/s and equal inlet and outlet gas velocities. Estimate the maximum number of stages required.

8. Explain procedure for matching the turbine and compressor?

9. An axial flow turbine has a blade speed at the mean diameter is 300 mps, and mass flow is 2.5 kg/s. The gas temperature at turbine inlet and outlet are 500 degrees and 300 degrees respectively. The fixed blade outlet angle is 20 degrees measured in the same direction of U. The axial velocity remains constant at 200 mps. Determine power developed.

10. The blades of free vortex turbine rotor have inlet and outlet angled of 60 degrees and 65 degrees at a mean diameter of 100 cm. The corresponding nozzle angle is 70 degrees. The hub tip ratio is 0.6 and the turbine runs at 3600 rpm. Calculate for the hub, mean and tip sections (a) Blade angles (b) Degree of reaction (c) Blade to gas speed ratio

UNIT II RAMJET PROPULSION

1. Explain the performance of ramjet engine?

2. Derive ideal efficiency for Ramjet engine.

3. Explain baffle type burner with neat sketch.

4. Explain the process involved in supersonic combustion ramjet engine.

5. Explain typical modes of inlet operation?

6. Explain can type of burner with neat sketch.

7. Discuss the problems associated with the supersonic combustion process?

8. A ramjet engine operates at M= 1.2 at an altitude of 6500 m. The diameter of the inlet diffuser at entry is 50 cm and stagnation temperature at the nozzle entry is 15oo K. The C.V of the fuel used is40 MJ/kg. The properties of the combustion gases are same as that of the air (γ=1.4,

R=287 J/kg K). The velocity of air at the diffuser exit is negligible. Calculate the

i) The efficiency of ideal cycle ii) Flight speed

iii) Air flow rate

iv) Diffuser pressure ratio v) Fuel air ratio

vi) Nozzle jet Mach number

The efficiency of diffuser is 0.9, combustor = 0.98, nozzle = 0.96

9. A ramjet engine propels on an aircraft at Mach no = 1.4 and at an altitude of 6ooo m. the diameter of inlet diffuser at the entry is 40 cm and C.V of fuel is 43 MJ/kg. The stagnation temperature at the nozzle entry is 1500 K.

The properties of combustion gases are same as those of air (γ=1.4 , R=287

J/kg K). Find

i) Efficiency of ideal cycle ii) Flight speed

iii) Air flow rate

iv) Diffuser pressure ratio v) Fuel air ratio

vi) Nozzle pressure ratio

vii) Nozzle jet Mach number viii) Propulsive efficiency

ix) Thrust

Efficiency of diffuser is 0.92 , combustor is 0.97 , nozzle is 0.95 and combustor pressure loss is 0.22.

10. A ramjet engine flies at an altitude of 6500 m and the flight Mach number is 4. The data for the engine is given below.

i) Air fuel ratio = 52

ii) C. V. of fuel = 44 MJ/kg

iii) Diffuser inlet diameter = 0.48 m iv) Efficiency of diffuser = 0.85

v) Efficiency of combustor = 0.97

vi) Efficiency of nozzle =

0.96 Calculate

1. Ideal cycle efficiency

2. Flight speed

3. Air fuel consumption

4. Diffuser pressure ratio

5. Maximum engine temperature

6. Nozzle pressure ratio

7. Exit Mach number

8. Thrust

9. Air specific impulse

10. Thrust specific fuel ratio

UNIT III FUNDAMENTALS OF ROCKET PROPULSION

1. A rocket flies at a speed of 10,000 kMph with an effective exhaust velocity of 1350 m/s and the heat produced by the propellant is 6600 KJ / kg. If the propellant flow rate is 4.8 kg/s, determine,

(i) Propulsive efficiency (ii) Propulsive power (iii) Engine output

(iv) Thermal efficiency

(v) Overall efficiency

2. Derive propulsive efficiency for rocket engine.

3. A rocket is to be designed to produce 5 MN thrust at sea level. The pressure in the combustion chamber is 7 MPa and the temperature is 2800K. If the working fluid is assumed to be a perfect gas with the properties of air at room temperature, determine the following:

(i) Specific impulse (ii) Mass flow rate (iii) Throat diameter (iv) Exit diameter

4. Explain conical nozzle with neat sketch.

5. Explain bell nozzle with suitable sketch.

6. Describe the working principle of typical rocket engine with neat sketch.

7. Derive thrust equation for rocket engine.

8. A rocket nozzle has a throat area of 20 cm2, combustion chamber pressure of 24 bar and weight flow rate is 45 N/s. If the specific impulse is 128 seconds. Find

(i) Thrust coefficient

(ii) Propellant weight flow coefficient (iii)Specific propellant consumption (iv) Characteristic velocity

9. A rocket engine has following data: Propellant flow rate = 5.1 kg / s Nozzle exit diameter = 11 cm

Nozzle exit diameter = 1.03 bar Ambient pressure = 1.013 bar Thrust chamber pressure = 20 bar

Thrust = 6.8 KN. Find the following: (i) Exit Mach number

(ii) Nozzle area ratio

(iii)Throat area

(iv) Thrust coefficient

(v) Propellant weight flow coefficient

(vi) Characteristic velocity. Take specific heat ratio as 1.3.

UNIT IV CHEMICAL ROCKETS

1. With the help of a schematic diagram, explain elaborate scheme of a typical turbo pump feed system.

2. Explain the hardware components of solid propellant rocket engine with neat sketch and explain its working principle.

3. What are the advantages of liquid propellant system over solid propellant system?

4. List and very briefly explain the methods of cooling adopted for rocket motors.

5. Explain strand burner with diagram

6. Describe the working of liquid propellant rocket engine with neat sketch.

7. Describe the working of solid propellant rocket engine with neat sketch?

8. With the help of a schematic diagram, explain elaborate scheme of a gas pressure feed system.

9. What are the important factors that influence the burning rate of a solid propellant? Explain.

10. Briefly explain about selection criteria of solid propellants?

UNIT V

1. Explain briefly about propellant grain design consideration?

2. Explain combustion process in rocket engine?

3. Explain briefly about hybrid propellant rocket engine with diagram?

4. Explain briefly about arc plasma rocket engine?

5. Explain briefly about Ion rocket engine?

6. Briefly explain about selection criteria of liquid propellants?

7. Explain briefly about Thrust vector control?

8. Briefly explain about the nuclear rocket engine with diagram?