What are the different types of aircraft engines?

• Turboprop engine:- In the turboprop engine the expansion of gases takes place partly in the turbine (80 per) and partly(20 per) in the nozzle. The power developed by the turbine is consumed by running the compressor and the propeller. The propeller and jet produced by the nozzle give forward motion to aircraft. The turbine potential the advantages of turbojet and propeller (I.e. High Power for take-off and high propulsion efficiency at speeds below 600 km/h ). The overall efficiency of the turboprop is improved by providing the diffuser before the compressor. The pressure rise takes place in the diffuser. This pressure rise takes place due to the conversion of the kinetic energy of the incoming air equal to aircraft velocity into the type of compressor is known as ram effects.

• Ramjet engine:- Ramjet is also called a tho did login tube or flying s love pipe. Ramjet engines can fly at supersonic speeds. In ram jet engine compressor and turbine are not necessary as the entire compression depends only on the ram compression. 

               The ramjet engine consists of a diffuser that is used for compression and combustion chamber and nozzle. The air enters the ramjet plant with supersonic speed and is slowed down to sonic velocity in the supersonic diffuser, consequently, the pressure suddenly increases in the supersonic diffuser to the formation of the shock wave. The pressure of air is further increased in the supersonic diffuser increasing the temperature of the air above the ignition temperature. 

In the combustion chamber,  the fuel is injected through the injection nozzle. The fuel-air mixture is then ignited using a spark plug and combustion temperatures of the order of 2000k are attained. The expansion of gases towards the diffuser entrance is rest ride by pressure barrier at the after the end of the diffuser and as a result, the hot gases are constrained to move towards the nozzle and undergo expansion the pressure energy is converted into the kinetic energy. The high-velocity gases leaving the nozzle provide forward thrust to the unit.
The best performance of ramjet engines is obtained at a fight speed of 1700 km/h to 2000 km/h.

• Pulse Jet Engine: -A pulse jet engine is an intermittent combustion engine and it operates on a cycle similar to a reciprocating engine. Whereas the turbojet and ramjet engines are continuous in operation and are based on the Brayton cycle. A pulse jet engine like an athodyd develops thrust by a high velocity of the jet of exhaust gases without the aid of a compressor or turbine. Its development is primarily due to self-starting. 
• The incoming air is compressed by the ram effect in the diffuser section and the grid passage which are opened and closed by V-shaped non-return values.
• The fuel is then injected into the combustion chamber by fuel injectors (worked from the air pressure from the compressed air battles). The combustion is then initiated by a spark plug (once the engine is operating normally, the spark is turned off and the residual flame in the combustion chamber is used for combustion.

As a result of combustion(of the mixture of air and fuel) the temperature and pressure of combustion products increase. Because the combustion pressure is higher than ram pressure, the non-return valve gets closed and consequently, the hot gases flow out of the tailpipe, with a high velocity, and in doing so, give a forward thrust to the unit.