Question

what is an indicator diagram mention it's use​

Answer 1

Indicator diagrams, previously called PV diagrams(Pressure Volume diagrams) is a graphical representation of a thermodynamic system using P and V. They are used to assess the overall performance of the main engine of a marine vehicle. They are drawn by a mechanical apparatus called an “indicator”.

A pressure–volume diagram (or PV diagram, or volume–pressure loop) is used to describe corresponding changes in volume and pressure in a system. They are commonly used in thermodynamics, cardiovascular physiology, and respiratory physiology.