Acoustic radiation from a circular pipe with an infinite flange

Abstract

The reflection of sound from the end of a flanged pipe is solved in a manner simpler than the procedure of Nomura et al. (1960 Journal of the Physical Society of Japan 15, 510-517). Numerical calculations give the low-frequency end correction length as 0·82159... radii, which is very close to Rayleigh's conjectured value of 0·82 radii. The power gain in the transmitted region is illustrated as a function of angle for frequencies below the first cut-off. The related problem of the acoustic response in a flanged pipe when a plane wave is incident upon the pipe in the axial direction is also discussed. Some approximate formulae are presented for the reflection coefficients of flanged and unflanged pipes. © 1989.