The engine is a machine capable of transforming a source of energy, which can be in chemical form (in the presence of a fuel), electrical or thermal, into a mechanical energy or mechanically continuous work, typically used in the field application purposes. with the propulsion of various types of vehicles.
In a philosophical sense, an engine is the organism that causes movement or change in other affiliated institutions: Aristotle spoke of motionless motor, a term also picked up by other philosophers, to indicate the cause of the universe, that is, the object or subject which (according to his philosophy) was at the beginning.
The engine is also used in computer science (graphic engine, search engine, database engine ...) to designate a program that "automatically and constantly" transforms something into something else. More precisely in computing, an engine is a program that, during its normal operation:
- never ends, unless you have technical problems or are not deliberately arrested;
- process your output from a set of predefined data and / or procedures;
- It is meant to be used by other programs and not directly by humans
General principles of the engine
All actual physical engines of any kind are subject to the laws of energy conservation and the fact that energy on the road is dispersed and, therefore, will provide a total work less than the energy contained in the spent fuel for its operation. for example, in thermodynamics, the relationship between the work provided and the energy expended by a particular engine is its gross performance, which comprises the fraction of energy expended for the internal operation of the engine. It is always less than the thermodynamic efficiency, the efficiency (not measured, but calculated) for an identical motor considered "ideal", that is, without internal energy dissipation.
In particular, the efficiency of the thermal motors depends strictly on the initial and final temperature of their cycle, and for a given temperature jump (& Delta; T will however be less than the Carnot cycle in the same & Delta; T).
Most commonly used motors are alternative and / or rotary, and produce work in the form of torque or force on an axis; others produce only a linear force.
History of the engine
One of the primary engines as it is understood today was the steam engine, in which it is the product of superheated steam in a boiler which then, expanding in a cylinder, produces a thrust in a piston. Such movement, alternative made with other mechanical devices, can be transferred to a wheel or a flywheel through a connecting rod-crank mechanism, in order to make possible the movement of the vehicle. During the nineteenth century steamships replaced sailboats and towards the end of the same century the development of the internal combustion engine made possible the great development of the automotive industry and, later, the birth of the aeronautical industry.
After the Second World War, the use for aeronautical flight called for the development of jet engines, while the birth of space flights made widespread development of rocket engines and, in particular, a chemical rocket engine.
In recent years, interplanetary flight requirements are driving research into new solutions, particularly in the field of non-chemical rocket engines such as space sails.
In the field of motors for automotive applications, research is strongly oriented towards solutions that reduce consumption and emissions of pollutants to the environment