Propulsion: Propulsion is the act to drive a propulsive vehicle forward by producing thrust in flight. Thrust force is developed based on the Newton’s laws of motion.
Propulsive System: It is a machine (engine) that produces thrust to push an object forward. The propulsive system drives the aircraft forward by displacement of working fluid (air & fuel/combustion products) in direction opposite to that in which an airplane is propelled.
Chemical Propulsive systems burn the fuel, whereby the energy stored in the chemical bonds is released; and this energy, in the form of heat, is converted into mechanical motion.
Propulsive Systems (Engines) are broadly grouped into
- Internal Combustion Engines
- External Combustion Engines
- Air Breathing Engines
- Non-air breathing Engines
Internal Combustion Engines:
- Combustion of fuel occurs in the engine cylinder
- Combustion is usually intermittent
- 1Fresh mixture of air & fuel is taken in again
External Combustion Engines:
- Internal working fluid (air & fuel) is heated by combustion products of an external source in a heat exchanger
- The heated working fluid is expanded to provide the useful force to propel the deviceThe working fluid is then cooled, compressed and reused