The engine classification includes several large groups of these devices. It is worth noting that each individual group, in turn, is divided into several more smaller ones. This is justified by the fact that today man has invented a huge number of various kinds of engines.
The method of preparation of the mixture
The classification of internal combustion engines can also be carried out by the way the fuel was prepared for their operation. For example, two main types are distinguished - those with external mixture formation and with internal mixture formation. Mixture formation refers to the process by which fuel is obtained for engine operation. By external mixture formation is meant the process of preparing fuel for the engine to operate outside its limits, that is, in a carburetor or in a mixer. Naturally, this group includes those types of these devices that are not able to produce the mixture on their own.
The internal mixture formation refers to the case when the production process of the mixture occurs directly in the cylinder of the engine.
Liquid fuel
Liquid fuel engines are a type of rocket engine, that is, they are used to launch rockets. Such a device consists of the following parts:
- Combustion chamber with nozzle. These elements serve to convert the chemical energy of fuel into heat. After the completion of this process, the next one begins, the essence of which is the subsequent conversion of the already existing thermal energy into kinetic. It is important to note here that the combustion chamber, like the nozzle and the injection device, are considered a separate unit.
- The following elements are the fuel control valves, as well as the engine itself. The purpose of these valves, as the name implies, is to adjust the fuel supply. This is a fairly important process, since the characteristic of an engine like this depends on the amount of fuel supplied. Depending on the amount of working substance entering the engine, its thrust will change.
Liquid Fuel Devices
In the classification of engines with liquid matter as fuel, they are classified as a group of rocket devices. It is important to note that a wide variety of fuels can be used as the working fluid. Here it is necessary to understand that the choice of a mixture for starting the unit will depend on the characteristics, purpose, power, and also on the duration of the engine itself.
Among all the requirements that are most often applied to this particular class of devices, this is the lowest consumption of the working mixture or, what is the same thing, the maximum specific thrust. When it becomes necessary to choose a mixture for running an engine on liquid fuel, pay attention to such parameters as: ignition and combustion rate, density, volatility, toxicity, viscosity, and some other important characteristics.
Solid fuel unit
The classification of engines includes another type of device. These units operate on slightly unusual, solid fuel. It is important to note here that the scope of these engines is also missile. Gunpowder became the main substance that is the fuel for this device. The peculiarity of the work lies in the fact that the unit works until it runs out of stock until the end. The very same powder is placed directly in the combustion chamber of the engine. Such devices became known as solid propellant rocket engines, or solid propellant rocket engines.
It is important to note here that this particular class of engines is one of the oldest. In addition, it was this type of device that became the first to find its practical application. Another important fact is that smoke powder was previously used as fuel. With the development of technology, the look of the mixture has changed. People managed to invent smokeless powder for use as fuel for rocket engines.
Fuel-free engine
One of the rather interesting classes of the unit is an engine that does not use any fuel mixture for its operation. Most often, these types of devices are used as rotation drives. This unit consists of such parts as: a disk or a flywheel, which is fixed on the axis. On the same part there is one or several permanent rotor magnets.
An important condition is that these magnets, like the disk itself or the flywheel, must be installed so that nothing interferes with their free rotation around its axis. Another key part of a fuel-free engine is the cylindrical permanent magnet of the stopper, which is fixedly mounted on a rod mounted parallel to the disk or flywheel. The permanent cylindrical magnet can, together with the rod, move to the area where at the given moment there is a magnetic field created by the rotor magnets.
The principle of operation of the fuel-free unit
The principle of operation of this device is that all of its magnets are rotated by the same poles towards each other. Since the magnetic poles of the same name will always be repelled from each other, their movement will cause the disk or flywheel to rotate around its axis. In addition to this type of engine, there is another one that is very similar in its principle to working with a fuelless one.
Such a device was a magnetic motor, which has a stator in the form of a permanent magnetic ring, as well as a rotor (or it is also called an anchor). This element is a rod permanent magnet, which is placed inside the stator in the same plane.
The disadvantage of these types of engines is that they need power supply to carry out their work. When inventing this type of device, several goals were set. It was necessary to achieve an environmentally friendly type of engine that would not have harmful emissions during its operation, and also work without consuming any type of fuel and without supplying electric energy from external sources. At the same time, he also did not have to pollute the environment or atmospheric air.
Aircraft engines
Before proceeding with the description of a specific class of engines, it is best to figure out by what principle they are separated. Currently, this group is classified into two fundamentally different types. The only distinguishing feature of one group from another was the ability of the device to operate outside the atmosphere. In other words, the first category of units requires an atmosphere for its work, the second is not tied to this indicator and can be operated outside its limits. The first group is called atmospheric or air, the second is called rocket.
It is worth noting that, conditionally, these types of devices are called as rotary air engines and aircraft jet engines.
Reactive device group
The second category of devices, i.e. reactive, includes such units as: turbojet air engines, ramjet engines. The main difference between these two types of devices is that in direct-flow reactive devices, air compression occurs due to the supply of mechanical energy to the engine path. For the operation of this unit, it is necessary to create increased static pressure. This effect is achieved by braking, moving in the intake device of the air intake, air.
Bypass reactive
A jet engine of this type of aircraft - a dual-circuit turbojet - was born due to the fact that people needed to create a device that would have an increased traction efficiency. To achieve an increase in this indicator, it was necessary at huge subsonic speeds. The principle of operation of this device looks something like this.
Air flows onto the engine, then it enters the air intake, where it is divided into several parts. One part passes through a high-pressure device located in the primary circuit. The second part of the intake air passes through the fan blades in the second circuit. It is worth noting that the principle of constructing the first circuit in the engine turbofan engine is similar to that used in the circuit of its predecessor turbofan engine, and therefore it works accordingly. But the action of a fan located in the second circuit of the engine is similar to how a multi-blade propeller functions, which rotates in an annular channel.
We can add that it is possible to use the turbofan engine also at supersonic speeds, but for this it is necessary to provide for the presence of a fuel combustion system in its second circuit in order to increase the draft of the device.