The document summarizes the key components and operation of a liquid propellant rocket engine. It discusses that a liquid propellant rocket engine uses liquid fuel (like refined petrol or liquid hydrogen) and liquid oxygen that are pumped into a combustion chamber along with a preheated fuel-oxidizer mixture. The combustion of this mixture in the chamber produces high pressure and temperature gases that are expanded through a nozzle to produce high velocity thrust. Some advantages are reusability, controllability, and high specific impulse for long range operations. Disadvantages include more complex construction, higher costs, safety issues, larger size, and need for vibration insulation.

1. UNIT V
LIQUID PROPELLANT ROCKET ENGINE
BY
Dr. A. Asha
Professor/Mechanical Engineering
Kamaraj College of Engineering & Technology

2. LIQUID PROPELLANT ROCKET ENGINE
• Construction
(a) Liquid fuel (refined petrol, liquid hydrogen, hydrazine)
(b) Liquid oxygen
(c) Preheater : ( To preheat the fuel and oxygen which are
maintained at low temperatures)
(d) Nozzle : To increase the velocity and decrease the
pressure of the gases

4. WORKING
• Liquid fuel and liquid oxygen are pumped separately into a combustion
chamber through control valves
• Since the liquid fuel and liquid oxygen are stored at very low temperature
they are preheated in the preheater to a suitable temperature.
• The preheated fuel oxidizer mixture is injected into the combustion
chamber through suitable injector and combustion takes place.
• When the combustion takes place very high pressure and very high
temperature gases are produced
• The highly heated products pf combustion gases are then allowed to
expand in the nozzle section
• In the nozzle the pressure energy is converted to kinetic energy so the
gases coming out from the unit with very high velocity.

5. ADVANTAGES AND DISADVANTGES
• Advantages
1. Can be reused after recovery
2. Combustion process in controllable
3. Speed regulation is possible
4. High specific impulse
5. More economical for long range operations
6. Malfunctions and accidents can be rectified at any stage

6. DISADVANTGES
• Construction is more complicated
• Manufacturing cost is high‘
• Handling and safety problems
• The size and weight of the engine is more compared to solid
propellant rocket
• High vibration
• Proper insulation is needed