A jet engine is a so-called device designed to move, as a rule, in the air of the same device and, as a rule, coupled together with some kind of unit (flight apparatus).
The movement of the engine is carried out due to the thrust force, called reactive, which occurs when the energy of various substances or fuels (electricity, chemical, nuclear) is converted. The reactive force of the outflowing jets giving off their energy and generated at the outlet nozzle of the device is capable of driving the entire apparatus without the help of extraneous units and mechanisms. A perfect Bellmouth fitting is also an essential part of the jet engine.
The very theory of the practical application of the energy of reactive force, which would cope with the gravity of the Earth, was proposed by the scientist-engineer from Russia Tsiolkovsky K.E. However, it took the scientist a lot of time, including the political change of power, for his scientific research to be taken into practical use.
How a jet engine works
In general, the principle of operation of a jet engine is practically similar to the principle of operation of a nuclear engine. For the first, chemical motive energy is used, for the other, the energy of nuclear elements.
Many of us, especially the male half of the population (in the army, on the hunt, in the shooting range, at the range), fired from firearms and, accordingly, felt the effect of reactive force in the form of recoil. The same principle, based on the law of conservation of momentum, is applied in jet propulsion systems, in which the main propellant is fuel.
If we consider the option of a jet engine operating on kerosene fuel, then in the mixing compartment of the unit, where the fuel is mixed with the oxidizer and the composition is burned, enormous energy is released in the form of heat and an instant increase in pressure 10-20-30 or more times higher than atmospheric.
How Fuel and Oxygen Mixture Help Jet Engines?
With a constant supply of fuel and oxidizer (air, liquid oxygen, nitric acid), the output kinetic energy of the working exhaust mixture will have a high driving impulse. And the outflowing jets through the “Laval” nozzle of the unit into the surrounding space will set the unit in motion due to the pushing moment.
Air from the surrounding space enters the suction fans, which feed it further to the blades of the turbocharger rotating at a very high speed. In this case, the incoming air performs 2 functions:
- oxidizer for fuel combustion;
- unit cooler.
In the turbocharger blades, the air is tightly compacted and under high pressure (from 3 MPa) is supplied to the fuel mixing chamber of the jet engine. Figure 3 shows that the combustion chamber is designed in such a way that the air is mixed in several stages – at the inlet and in the chamber itself. Fuel is also supplied here.