a graphical or other representation of the cyclic variations of pressure and volume within the cylinder of a reciprocating engine obtained by using an indicator
indicator diagram in Automotive Engineering
(ɪndɪkeɪtər daɪəgræm)
Word forms: (regular plural) indicator diagrams
noun
(Automotive engineering: Design and performance)
An indicator diagram is a map of cylinder pressure plotted against stroke or degrees of rotation for the power stroke or complete cycle of an engine.
The fuel/air ratio of the charge influences the rate of combustion and has an effecton indicator diagrams.
If you measure the area under the indicator diagram, you can find out the power the engine is producing.
Indicator diagrams used to be drawn by a mechanical apparatus called an indicator, which is why theystill have this name.