what is meant by mean piston speed. explain it's importance .
Answers
The mean piston speed is the average speed of the piston in a reciprocating engine. It is a function of stroke and RPM. There is a factor of 2 in the equation to account for one stroke to occur in 1/2 of a crank revolution (or alternatively: two strokes per one crank revolution) and a '60' to convert seconds from minutes in the RPM term.
MPS = 2 * Stroke * RPM / 60
For example, a piston in an automobile engine which has a stroke of 90 mm will have a mean speed at 3000 rpm of 2 * (90 / 1000) * 3000 / 60 = 9 m/s.
It is a good indicator of the class and performance of an engine relative to its competitors. The 5.2-liter V10 that debuted in the 2017 Audi R8 has the highest mean piston speed for any production car (26.9 m/s) thanks to its 92.8 mm stroke and 8700-rpm redline.[1]
Corrected Piston Speed (Frederick Lanchester and Janke and King) Corrected Piston speed is a method to more accurately represent stress on an engine, and is calculated as mean piston speed divided by the square root of the stroke/bore ratio.