The Effect of Silencers of the Helmholtz-Resonator Type on Pressure Waves of Finite Amplitude: Single Pressure Pulses

Abstract

The attenuation of large-amplitude waves effected by silencers of the so-called Helmholtz-resonator type is envisaged as being due to the finite efflux of gas through the holes of the silencer with resulting partial reflection, and hence reduced transmission, of the incident wave. Quasi-steady, one-dimensional flow arguments are used to predict the attenuation, the flow conditions being assumed reversible and adiabatic, that is, isentropic. This latter assumption is avoided in an alternative method by assuming a knowledge of the relationship between pipe Mach numbers and the pressure difference in the pipe across the holes. Indicator diagrams resulting from single pulse experiments are, in general, in good agreement with those predicted.