Code No: RR410306

Set No. 1

Code No: RR410306

IV B.Tech I Semester Supplimentary Examinations, February 2008 JET PROPULSION AND ROCKET ENGINEERING (Mechanical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Explain with neat sketches the working of a simple constant pressure open cycle gas turbine. (b) What are the advantages and disadvantages of a closed cycle gas turbine over open cycle gas turbine? What are the desirable properties of working fluid suitable for closed cycle operation? [8+8] 2. (a) What is meant by jet propulsion? What are the basic differences between jet propulsion cycle and shaft power cycle? (b) The exit velocity from a jet unit is 650 m/s from an air flow of 40 kg/s through the unit. The air craft is flying at 250 km/hr. Calculate the thrust developed, the thrust power and the propulsion efficiency. Neglect the effect of fuel. [8+8] 3. An Aircraft flies at 960 kmph. One of the its turbojet engines takes in 40 kg/s of air and expands the gases to the ambient pressure. The air fuel ratio is 50 and the lower calorific value of the fuel is 43 MJ/Kg. For maximum thrust power determine (a) Jet velocity (b) thrust (c) specific thrust (d) thrust power (e) propulsive, thermal, overall efficiencies and TSFC.

[16]

4. (a) Draw the sketch of a pulse jet engine. Write down its main advantages and disadvantages. (b) Describe the working of a scramjet engine. What is its advantages over the ram jet engine. [8+8] 5. Explain the working principle of a hybrid rocket engine with a neat diagram? List its applications. [16] 6. Draw the neat diagram of liquid propellant rocket engine? Compare with the principle of operation with solid propellant rocket engine? [16] 7. (a) Draw a neat sketch of turbo pump feed system employed in rockets. (b) How does cavitation occur in this system and what measures are taken to prevent it? 1 of 2

Set No. 1

Code No: RR410306

(c) What is the effect of cavitations on the operation of the rocket?

[6+6+4]

8. (a) With the help of a neat diagram, explain the working of liquid bi-propellent gas pressurization system. (b) Discuss the possibility of rocket-powered vehicle having a flight velocity greater than the exhaust velocity of the rocket motor. [8+8] ⋆⋆⋆⋆⋆

2 of 2

Set No. 2

Code No: RR410306

IV B.Tech I Semester Supplimentary Examinations, February 2008 JET PROPULSION AND ROCKET ENGINEERING (Mechanical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Draw the schematic diagram of simple cycle with inter cooler and explain briefly the working principle. Draw also P-v and T-s diagrams of the cycle. (b) A gas turbine is supplied with 60 kg/sec of gas at 5 bar and 8000 C and expands isentropically to 1 bar. Take the mean specific heats of the gas at constant pressure and constant volume to be 1 kJ/kgK and 0.717 kJ/kg K respectively. Calculate the exhaust gas temperature and power developed in Mw. [6+10] 2. (a) Explain the principle of jet propulsion and how you determine the thrust. (b) Explain clearly the various efficiencies associated with propulsion devices. [8+8] 3. Calculate the air flow rate through the engine, cross section area of the propelling nozzle exit, thrust, thrust power, propulsive and overall efficiencies for a turbojet engine from the following data, flight mach number = 0.85, flight altitude = 12000 m, cross sectional area of the inlet - diffuser at entry = 0.5 m2 . Air fuel ratio = 60, conditions at the exit of the exhaust jet, pressure = 477 bar, temperature = 1000k, velocity = 660 m/s, calorific value of the fuel = 43 MJ /kg. [16] 4. (a) Draw the sketch of a pulse jet engine. Write down its main advantages and disadvantages. (b) Describe the working of a scramjet engine. What is its advantages over the ram jet engine. [8+8] 5. (a) What are the requirements of an ideal rocket propellant? (b) Derive the equation for calculation of effective jet velocity in rocket?

[8+8]

6. (a) Compare liquid propellant rocket engine with solid propellant rocket engine? (b) What are different applications of solid propellant rocket engines?

[8+8]

7. (a) Describe briefly three important applications of rocket propulsion. (b) What is the purpose of injectors in rocket engines? Describe an injector with the aid of sketch. [4+12] 8. (a) With the help of a neat diagram, write about nuclear rocket engine. (b) What are the advantages it has over other rocket engines. ⋆⋆⋆⋆⋆

1 of 1

[8+8]

Set No. 3

Code No: RR410306

IV B.Tech I Semester Supplimentary Examinations, February 2008 JET PROPULSION AND ROCKET ENGINEERING (Mechanical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. The gas turbine takes air at 150 C the pressure ratio is 4 and maximum temperature is limited to 5600 C. Assuming isentropic efficiencies of compressor and turbine as 83% and 86% respectively. Determine the overall efficiency (a) with out heat exchanger and (b) with heat exchanger of an effectiveness of 0.75.

[16]

2. (a) Discuss the advantages and disadvantages of jet propulsion over other systems. (b) Give the complete classification of thermal jet engines. (c) ‘Rockets are non-atmospheric thermal jet engines’. Justify the statement. [6+4+6] 3. Calculate the air flow rate through the engine, cross section area of the propelling nozzle exit, thrust, thrust power, propulsive and overall efficiencies for a turbojet engine from the following data, flight mach number = 0.85, flight altitude = 12000 m, cross sectional area of the inlet - diffuser at entry = 0.5 m2 . Air fuel ratio = 60, conditions at the exit of the exhaust jet, pressure = 477 bar, temperature = 1000k, velocity = 660 m/s, calorific value of the fuel = 43 MJ /kg. [16] 4. (a) Describe the working of a ramjet engine. (b) Depict the various thermodynamic processes occurring in it on h-S diagram. (c) What is the effect at flight mach number on its efficiency. [8+4+4] 5. (a) Discuss the possibility of rocket powdered vehicle having a flight velocity greater than the exhaust velocity of the rocket motor? (b) What are different types of rocket engines? Explain. [8+8] 6. Sketch the layout of liquid propellant rocket engine and explain its working. Give its applications. [16] 7. (a) Describe briefly three important applications of rocket propulsion. (b) What is the purpose of injectors in rocket engines? Describe an injector with the aid of sketch. [4+12] 8. (a) What is the working principle of plasma arc rocket engine? (b) What are the basic components of the plasma arc rocket engine. Explain the function of each. [8+8] ⋆⋆⋆⋆⋆ 1 of 1

Set No. 4

Code No: RR410306

IV B.Tech I Semester Supplimentary Examinations, February 2008 JET PROPULSION AND ROCKET ENGINEERING (Mechanical Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. In an open cycle constant pressure gas turbine air enters the compressor at 1.02 bar and 270 C. The pressure of air after the compression is 4 bar. The isentropic efficiencies of compressor and turbine are 78% and 85% respectively. The air fuel ratio is 80:1. Calculate the power developed and thermal efficiency of the cycle if the flow rate of air is 2.5 kg/sec. Take Cp = 1.005 kJ/kgk, r = 1.4 for air and Cp = 1.147 kJ/kg. and r = 1.33, for gasses, R = 0.287 kJ/kgk. C.V. of fuel = 42000 kJ/kg. [16] 2. (a) What is meant by jet propulsion? What are the basic differences between jet propulsion cycle and shaft power cycle? (b) The exit velocity from a jet unit is 650 m/s from an air flow of 40 kg/s through the unit. The air craft is flying at 250 km/hr. Calculate the thrust developed, the thrust power and the propulsion efficiency. Neglect the effect of fuel. [8+8] 3. (a) What do you mean by Thrust Augmentation (b) What are the different methods of thrust Augmentation ? Explain each methods. [4+12] 4. (a) How ram rocket combines the desirable characteristics of a racket and a ram jet (b) Discuss various performance curves of altitude with Mach number and Net thrust for Ram jet engine. [8+8] 5. Explain the working principle of a hybrid rocket engine with a neat diagram? List its applications. [16] 6. (a) What are the difference between gas pressurization system and pump pressurization system? (b) What are different combinations of liquid bipropellants? Explain.

[8+8]

7. (a) Define the following quantities, write down their formulae and units: specific impulse, total impulse, and specific propellant consumption. (b) Calculate thrust, specific impulse, propulsive, thermal and overall efficiencies of a rocket engine from the following data: Effective jet speed = 1250m/s. Flight to jet speed ratio = 0.80 Oxidizer flow ratio = 3.5 kg/s 1 of 2

Set No. 4

Code No: RR410306

Fuel flow rate = 1.0 kg/s Heat of reaction per kg of exhaust gases = 2500 KJ/kg.

[8+8]

8. (a) What is the working principle of plasma arc rocket engine? (b) What are the basic components of the plasma arc rocket engine. Explain the function of each. [8+8] ⋆⋆⋆⋆⋆

2 of 2