reduce smoke Saab
Jet engines use a number of rows
Main article: Jet engine
Turbofan Jet Engine
Jet engines use a number of rows of fan blades to compress air which then enters a combustor where it is mixed with fuel (typically JP fuel) and then ignited. The burning of the fuel raises the temperature of the air which is then exhausted out of the engine creating thrust. A modern turbofan engine can operate at as high as 48% efficiency. 24
There are six sections to a Fan Jet engine:
Intake, induction or suction: The intake valves are open as a result of the cam lobe pressing down on the valve stem. The piston moves downward increasing the volume of the combustion chamber and allowing air to enter in the case of a CI engine or an air fuel mix in the case of SI engines that do not use direct injection. The air or air-fuel mixture is called the charge in any case.
Compression: In this stroke, both valves are closed and the piston moves upward reducing the combustion chamber volume which reaches its minimum when the piston is at TDC. The piston performs work on the charge as it is being compressed; as a result its pressure, temperature and density increase; an approximation to this behavior is provided by the ideal gas law. Just before the piston reaches TDC, ignition begins. In the case of a SI engine, the spark plug receives a high voltage pulse that generates the spark which gives it its name and ignites the charge. In the case of a CI engine the fuel injector quickly injects fuel into the combustion chamber as a spray; the fuel ignites due to the high temperature.
Power or working stroke: The pressure of the combustion gases pushes the piston downward, generating more work than it required to compress the charge. Complementary to the compression stroke, the combustion gases expand and as a result their temperature, pressure and density decreases. When the piston is near to BDC the exhaust valve opens. The combustion gases expand irreversibly due to the leftover pressure?in excess of back pressure, the gauge pressure on the exhaust port?; this is called the blowdown.
Exhaust: The exhaust valve remains open while the piston moves upward expelling the combustion gases. For naturally aspirated engines a small part of the combustion gases may remain in the cylinder during normal operation because the piston does not close the combustion chamber completely; these gases dissolve in the next charge. At the end of this stroke, the exhaust valve closes, the intake valve opens, and the sequence repeats in the next cycle. The intake valve may open before the exhaust valve closes to allow better scavenging.
Car - what does it mean?
The word "car" is believed to originate from the Latin word carrus or carrum ("wheeled vehicle"), or the Middle English word carre (meaning cart, from Old North French). In turn, these originated from the Gaulish word karros (a Gallic chariot). The Gaulish language was a branch of the Brythoic language which also used the word Karr; the Brythonig language evolved into Welsh (and Gaelic) where 'Car llusg' (a drag cart or sledge) and 'car rhyfel' (war chariot) still survive.1112 It originally referred to any wheeled horse-drawn vehicle, such as a cart, carriage, or wagon.1314 "Motor car" is attested from 1895, and is the usual formal name for cars in British English.3 "Autocar" is a variant that is also attested from 1895, but that is now considered archaic. It literally means "self-propelled car".15 The term "horseless carriage" was used by some to refer to the first cars at the time that they were being built, and is attested from 1895.16
The word "automobile" is a classical compound derived from the Ancient Greek word autós (?????), meaning "self", and the Latin word mobilis, meaning "movable". It entered the English language from French, and was first adopted by the Automobile Club of Great Britain in 1897.17 Over time, the word "automobile" fell out of favour in Britain, and was replaced by "motor car". It remains a chiefly North American usage.18 An abbreviated form, "auto", was formerly a common way to refer to cars in English, but is now considered old-fashioned. The word is still used in some compound formations in American English, like "auto industry" and "auto mechanic".