Release Process in a Four‐Stroke Engine: Theory and Experiment Applied to an Aspect of the Silencing Problem

THE problem of silencing the exhaust of a piston engine requires that attention be given to the two main sources of gas noise; firstly, relatively low frequency vibrations in the exhaust column itself, excited by a pressure pulse produced by the rapid rush of gas from the cylinder into the exhaust pipe, and, secondly, high frequency vibrations resulting from eddies in the gas stream.