The Influence of Exhaust Poppet Valve Gas Flow on Reciprocating Engine Noise

The far field noise generated by cold air flowing through stationary and reciprocating exhaust poppet valves into a cylindrical duct or pipe has been investigated. A method of predicting the intensity and frequency spectrum of the noise generated in such circumstances in terms of the known or assumed geometry and flow characteristics of the valves is presented. Comparisons of the predicted frequency spectra with measured values show good agreement for steady gas flows through stationary valves and for unsteady flow through a simplified exhaust system of a motored single cylinder internal combustion engine.