Editing Diesel cycle (section)

{{Short description|Engine combustion process}}
{{About|the thermodynamic cycle|diesel powered motorcycles|Diesel motorcycle}}
{{Thermodynamics|cTopic=Processes and Cycles}}
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The '''Diesel cycle''' is a combustion process of a reciprocating [[internal combustion engine]]. In it, [[fuel]] is ignited by heat generated during the compression of air in the combustion chamber, into which fuel is then injected. This is in contrast to igniting the fuel-air mixture with a [[spark plug]] as in the [[Otto cycle]] ([[four-stroke engine|four-stroke]]/petrol) engine. [[Diesel engine]]s are used in [[aircraft_diesel_engine|aircraft]], [[automobile]]s, [[power generation]], [[diesel–electric powertrain|diesel–electric]] [[locomotive]]s, and both surface [[ship]]s and [[submarine]]s.

The Diesel cycle is assumed to have constant pressure during the initial part of the combustion phase (<math>V_2</math> to <math>V_3</math> in the diagram, below). This is an idealized mathematical model: real physical diesels do have an increase in pressure during this period, but it is less pronounced than in the Otto cycle. In contrast, the idealized [[Otto cycle]] of a [[four-stroke cycle|gasoline engine]] approximates a constant volume process during that phase.